diff --git a/server/src/external/stripe/stripeSubUtils/getStripeSubItems.ts b/server/src/external/stripe/stripeSubUtils/getStripeSubItems.ts
index 621676e8d..92f23f6b3 100644
--- a/server/src/external/stripe/stripeSubUtils/getStripeSubItems.ts
+++ b/server/src/external/stripe/stripeSubUtils/getStripeSubItems.ts
@@ -34,6 +34,7 @@ import {
   priceToIntervalKey,
 } from "@/internal/products/prices/priceUtils/convertPrice.js";
 import { AttachParams } from "@/internal/customers/cusProducts/AttachParams.js";
+import { ItemSet } from "@/utils/models/ItemSet.js";
 
 const getIntervalToPrices = (prices: Price[]) => {
   const intervalToPrices: Record<string, Price[]> = {};
@@ -296,9 +297,21 @@ export const getStripeSubItems2 = async ({
     if (price.config.interval === BillingInterval.OneOff) {
       invoiceItems.push(lineItem);
     } else {
-      subItems.push(lineItem);
+      subItems.push({
+        ...lineItem,
+        autumnPrice: price,
+      });
     }
   }
 
-  return { subItems, invoiceItems, usageFeatures };
+  return { subItems, invoiceItems, usageFeatures } as ItemSet;
+};
+
+export const sanitizeSubItems = (subItems: any[]) => {
+  return subItems.map((si) => {
+    const { autumnPrice, ...rest } = si;
+    return {
+      ...rest,
+    };
+  });
 };
diff --git a/server/src/external/stripe/stripeSubUtils/stripeSubItemUtils.ts b/server/src/external/stripe/stripeSubUtils/stripeSubItemUtils.ts
index 7c5e889e1..94fc66c99 100644
--- a/server/src/external/stripe/stripeSubUtils/stripeSubItemUtils.ts
+++ b/server/src/external/stripe/stripeSubUtils/stripeSubItemUtils.ts
@@ -47,7 +47,8 @@ export const findStripeItemForPrice = ({
       } else {
         return (
           config.stripe_price_id == si.price?.id ||
-          config.stripe_product_id == si.price?.product
+          config.stripe_product_id == si.price?.product ||
+          config.stripe_empty_price_id == si.price?.id
         );
       }
     });
diff --git a/server/src/internal/customers/attach/attachFunctions/addProductFlow/createStripeSub2.ts b/server/src/internal/customers/attach/attachFunctions/addProductFlow/createStripeSub2.ts
index da94e31c4..dddd4eca4 100644
--- a/server/src/internal/customers/attach/attachFunctions/addProductFlow/createStripeSub2.ts
+++ b/server/src/internal/customers/attach/attachFunctions/addProductFlow/createStripeSub2.ts
@@ -9,6 +9,8 @@ import { DrizzleCli } from "@/db/initDrizzle.js";
 import { getAlignedIntervalUnix } from "@/internal/products/prices/billingIntervalUtils.js";
 import { getEarliestPeriodEnd } from "@/external/stripe/stripeSubUtils/convertSubUtils.js";
 import { AttachParams } from "@/internal/customers/cusProducts/AttachParams.js";
+import { sanitizeSubItems } from "@/external/stripe/stripeSubUtils/getStripeSubItems.js";
+import { ItemSet } from "@/utils/models/ItemSet.js";
 
 // Get payment method
 
@@ -35,11 +37,7 @@ export const createStripeSub2 = async ({
   attachParams: AttachParams;
   config: AttachConfig;
   anchorToUnix?: number;
-  itemSet: {
-    subItems: Stripe.SubscriptionItem[];
-    invoiceItems: any[];
-    usageFeatures: string[];
-  };
+  itemSet: ItemSet;
   earliestInterval?: IntervalConfig | null;
 }) => {
   const { customer, invoiceOnly, freeTrial, org, now, reward } = attachParams;
@@ -94,7 +92,7 @@ export const createStripeSub2 = async ({
     const subscription = await stripeCli.subscriptions.create({
       ...paymentMethodData,
       customer: customer.processor.id,
-      items: subItems as any,
+      items: sanitizeSubItems(subItems),
       // items: subItems as any,
       billing_mode: { type: "flexible" },
       trial_end: freeTrialToStripeTimestamp({ freeTrial, now }),
diff --git a/server/src/internal/customers/attach/attachFunctions/addProductFlow/handlePaidProduct.ts b/server/src/internal/customers/attach/attachFunctions/addProductFlow/handlePaidProduct.ts
index 7060edac3..994c20aa1 100644
--- a/server/src/internal/customers/attach/attachFunctions/addProductFlow/handlePaidProduct.ts
+++ b/server/src/internal/customers/attach/attachFunctions/addProductFlow/handlePaidProduct.ts
@@ -30,6 +30,9 @@ import { addBillingIntervalUnix } from "@/internal/products/prices/billingInterv
 import { getSmallestInterval } from "@/internal/products/prices/priceUtils/priceIntervalUtils.js";
 import RecaseError from "@/utils/errorUtils.js";
 import { handleCreateCheckout } from "@/internal/customers/add-product/handleCreateCheckout.js";
+import { getCustomerSub } from "../../attachUtils/convertAttachParams.js";
+import { paramsToSubItems } from "../../mergeUtils/paramsToSubItems.js";
+import { updateStripeSub2 } from "../upgradeFlow/updateStripeSub2.js";
 
 export const handlePaidProduct = async ({
   req,
@@ -74,68 +77,95 @@ export const handlePaidProduct = async ({
     );
   }
 
-  let mergeSub = await cusProductToSub({
-    cusProduct: mergeCusProduct!,
-    stripeCli,
-  });
+  // let mergeSub = await cusProductToSub({
+  //   cusProduct: mergeCusProduct!,
+  //   stripeCli,
+  // });
 
-  let billingCycleAnchorUnix = undefined;
-  if (attachParams.billingAnchor) {
-    billingCycleAnchorUnix = attachParams.billingAnchor;
-  }
-
-  const earliestInterval = getSmallestInterval({ prices: attachParams.prices });
+  const mergeSub = await getCustomerSub({ attachParams });
+  let sub: Stripe.Subscription | null;
 
+  // 1. If merge sub
   if (mergeSub) {
-    const { end } = subToPeriodStartEnd({ sub: mergeSub });
-    billingCycleAnchorUnix = end * 1000;
-  }
+    // Update
+    sub = mergeSub;
 
-  let newSub;
-  try {
-    newSub = await createStripeSub2({
-      db: req.db,
-      stripeCli,
+    const newItemSet = await paramsToSubItems({
+      req,
+      sub,
       attachParams,
-      itemSet,
-      anchorToUnix: billingCycleAnchorUnix,
-      earliestInterval,
       config,
     });
-  } catch (error: any) {
-    if (
-      error instanceof RecaseError &&
-      !invoiceOnly &&
-      error.code == ErrCode.CreateStripeSubscriptionFailed
-    ) {
-      return await handleCreateCheckout({
-        req,
-        res,
-        attachParams,
-        config,
-      });
+
+    const { updatedSub } = await updateStripeSub2({
+      req,
+      attachParams,
+      curSub: sub,
+      itemSet: newItemSet,
+      config,
+      fromCreate: true,
+    });
+
+    sub = updatedSub;
+
+    // 1.
+  } else {
+    // 2. If merge sub interval
+    let billingCycleAnchorUnix = undefined;
+    if (attachParams.billingAnchor) {
+      billingCycleAnchorUnix = attachParams.billingAnchor;
     }
 
-    throw error;
-  }
+    const earliestInterval = getSmallestInterval({
+      prices: attachParams.prices,
+    });
 
-  subscriptions.push(newSub);
+    if (mergeSub) {
+      const { end } = subToPeriodStartEnd({ sub: mergeSub });
+      billingCycleAnchorUnix = end * 1000;
+    }
 
-  const anchorToUnix = getEarliestPeriodEnd({ sub: newSub }) * 1000;
-
-  const batchInsertInvoice: any = [];
-  for (const sub of subscriptions) {
-    if (!sub.latest_invoice) continue;
-    batchInsertInvoice.push(
-      insertInvoiceFromAttach({
+    try {
+      sub = await createStripeSub2({
         db: req.db,
-        stripeInvoice: sub.latest_invoice as Stripe.Invoice,
+        stripeCli,
         attachParams,
-        logger,
-      })
-    );
+        itemSet,
+        anchorToUnix: billingCycleAnchorUnix,
+        earliestInterval,
+        config,
+      });
+    } catch (error: any) {
+      if (
+        error instanceof RecaseError &&
+        !invoiceOnly &&
+        error.code == ErrCode.CreateStripeSubscriptionFailed
+      ) {
+        return await handleCreateCheckout({
+          req,
+          res,
+          attachParams,
+          config,
+        });
+      }
+
+      throw error;
+    }
   }
-  const invoices = await Promise.all(batchInsertInvoice);
+
+  subscriptions.push(sub);
+
+  let invoice: Stripe.Invoice | undefined;
+  if (sub?.latest_invoice) {
+    invoice = await insertInvoiceFromAttach({
+      db: req.db,
+      stripeInvoice: sub.latest_invoice as Stripe.Invoice,
+      attachParams,
+      logger,
+    });
+  }
+
+  const anchorToUnix = getEarliestPeriodEnd({ sub }) * 1000;
 
   if (config.invoiceCheckout) {
     return {
@@ -176,7 +206,7 @@ export const handlePaidProduct = async ({
           product_ids: products.map((p) => p.id),
           customer_id: customer.id || customer.internal_id,
           invoice: invoiceOnly
-            ? attachToInvoiceResponse({ invoice: invoices?.[0] })
+            ? attachToInvoiceResponse({ invoice })
             : undefined,
         })
       );
@@ -186,7 +216,7 @@ export const handlePaidProduct = async ({
         message: `Successfully created subscriptions and attached ${products
           .map((p) => p.name)
           .join(", ")} to ${customer.name}`,
-        invoice: invoiceOnly ? invoices?.[0] : undefined,
+        invoice: invoiceOnly ? invoice : undefined,
       });
     }
   }
@@ -264,3 +294,17 @@ export const handlePaidProduct = async ({
 //     throw error;
 //   }
 // }
+
+// const batchInsertInvoice: any = [];
+// for (const sub of subscriptions) {
+//   if (!sub.latest_invoice) continue;
+//   batchInsertInvoice.push(
+//     insertInvoiceFromAttach({
+//       db: req.db,
+//       stripeInvoice: sub.latest_invoice as Stripe.Invoice,
+//       attachParams,
+//       logger,
+//     })
+//   );
+// }
+// const invoices = await Promise.all(batchInsertInvoice);
diff --git a/server/src/internal/customers/attach/attachFunctions/upgradeFlow/handleUpgradeFlow.ts b/server/src/internal/customers/attach/attachFunctions/upgradeFlow/handleUpgradeFlow.ts
index 061b7632c..25acd9366 100644
--- a/server/src/internal/customers/attach/attachFunctions/upgradeFlow/handleUpgradeFlow.ts
+++ b/server/src/internal/customers/attach/attachFunctions/upgradeFlow/handleUpgradeFlow.ts
@@ -23,6 +23,7 @@ import {
   getEarliestPeriodEnd,
   subToPeriodStartEnd,
 } from "@/external/stripe/stripeSubUtils/convertSubUtils.js";
+import { paramsToSubItems } from "../../mergeUtils/paramsToSubItems.js";
 
 export const handleUpgradeFlow = async ({
   req,
@@ -52,14 +53,23 @@ export const handleUpgradeFlow = async ({
     config,
   });
 
-  const newSubItems = await removeCurCusProductItems({
-    sub: curSub,
-    cusProduct: curCusProduct!,
-    subItems: itemSet.subItems,
+  // const newSubItems = await removeCurCusProductItems({
+  //   sub: curSub,
+  //   cusProduct: curCusProduct!,
+  //   subItems: itemSet.subItems,
+  // });
+
+  const newItemSet = await paramsToSubItems({
+    req,
+    sub: curSub!,
+    attachParams,
+    config,
   });
 
-  if (newSubItems.length > 0) {
-    itemSet.subItems = newSubItems;
+  const { subItems } = newItemSet;
+
+  if (subItems.length > 0) {
+    itemSet.subItems = subItems;
 
     logger.info(`1. Updating subs with new items`);
     const res = await updateStripeSub2({
diff --git a/server/src/internal/customers/attach/attachFunctions/upgradeFlow/updateStripeSub2.ts b/server/src/internal/customers/attach/attachFunctions/upgradeFlow/updateStripeSub2.ts
index 1c0f6522f..cef359813 100644
--- a/server/src/internal/customers/attach/attachFunctions/upgradeFlow/updateStripeSub2.ts
+++ b/server/src/internal/customers/attach/attachFunctions/upgradeFlow/updateStripeSub2.ts
@@ -11,6 +11,8 @@ import { createProrationInvoice } from "@/external/stripe/stripeSubUtils/updateS
 import { createAndFilterContUseItems } from "../../attachUtils/getContUseItems/createContUseInvoiceItems.js";
 import { freeTrialToStripeTimestamp } from "@/internal/products/free-trials/freeTrialUtils.js";
 import { getContUseInvoiceItems } from "../../attachUtils/getContUseItems/getContUseInvoiceItems.js";
+import { ItemSet } from "@/utils/models/ItemSet.js";
+import { sanitizeSubItems } from "@/external/stripe/stripeSubUtils/getStripeSubItems.js";
 
 export const updateStripeSub2 = async ({
   req,
@@ -18,15 +20,14 @@ export const updateStripeSub2 = async ({
   config,
   curSub,
   itemSet,
+  fromCreate = false,
 }: {
   req: ExtendedRequest;
   attachParams: AttachParams;
   config: AttachConfig;
   curSub: Stripe.Subscription;
-  itemSet: {
-    subItems: Stripe.SubscriptionItem[];
-    invoiceItems: Stripe.InvoiceItem[];
-  };
+  itemSet: ItemSet;
+  fromCreate?: boolean;
 }) => {
   const { db, logger } = req;
   const { curMainProduct } = attachParamToCusProducts({ attachParams });
@@ -52,9 +53,13 @@ export const updateStripeSub2 = async ({
   // 1. Update subscription
 
   let updatedSub = await stripeCli.subscriptions.update(curSub.id, {
-    items: itemSet.subItems,
+    items: sanitizeSubItems(itemSet.subItems),
     proration_behavior:
-      proration == ProrationBehavior.None ? "none" : "create_prorations",
+      proration == ProrationBehavior.None
+        ? "none"
+        : fromCreate
+          ? "always_invoice"
+          : "create_prorations",
     trial_end: trialEnd,
     default_payment_method: paymentMethod?.id,
     // add_invoice_items: itemSet.invoiceItems,
@@ -75,6 +80,13 @@ export const updateStripeSub2 = async ({
     };
   }
 
+  if (fromCreate) {
+    return {
+      updatedSub,
+      latestInvoice: curSub.latest_invoice as Stripe.Invoice,
+    };
+  }
+
   // 2. Create prorations for single use items
   let { invoiceItems, cusEntIds } = await createUsageInvoiceItems({
     db,
diff --git a/server/src/internal/customers/attach/attachUtils/convertAttachParams.ts b/server/src/internal/customers/attach/attachUtils/convertAttachParams.ts
index f514e346e..ec5b3142d 100644
--- a/server/src/internal/customers/attach/attachUtils/convertAttachParams.ts
+++ b/server/src/internal/customers/attach/attachUtils/convertAttachParams.ts
@@ -46,6 +46,64 @@ export const attachParamsToProduct = ({
   };
 };
 
+export const getCustomerSub = async ({
+  attachParams,
+}: {
+  attachParams: AttachParams;
+}) => {
+  const { stripeCli } = attachParams;
+  const fullCus = attachParams.customer;
+  let cusProducts = fullCus.customer_products;
+
+  const targetGroup = attachParams.products[0].group;
+  const targetEntityId = attachParams.internalEntityId || null;
+  const targetProductId = attachParams.products[0].id;
+
+  cusProducts.sort((a, b) => {
+    // 1. Check same group
+    const aGroupMatches = a.product.group === targetGroup;
+    const bGroupMatches = b.product.group === targetGroup;
+
+    if (aGroupMatches && !bGroupMatches) return -1;
+    if (!aGroupMatches && bGroupMatches) return 1;
+
+    // 2. Check main product
+    const aMain = !a.product.is_add_on;
+    const bMain = !b.product.is_add_on;
+
+    if (aMain && !bMain) return -1;
+    if (!aMain && bMain) return 1;
+
+    // 3. Check same product
+    const aProductIdMatches = a.product.id === targetProductId;
+    const bProductIdMatches = b.product.id === targetProductId;
+
+    if (aProductIdMatches && !bProductIdMatches) return -1;
+    if (!aProductIdMatches && bProductIdMatches) return 1;
+
+    // 4. Check same entity
+    const aEntityIdMatches = (a.internal_entity_id || null) === targetEntityId;
+    const bEntityIdMatches = (b.internal_entity_id || null) === targetEntityId;
+
+    if (aEntityIdMatches && !bEntityIdMatches) return -1;
+    if (!aEntityIdMatches && bEntityIdMatches) return 1;
+
+    return 0;
+  });
+
+  const subId = cusProducts.flatMap((cp) => cp.subscription_ids || [])?.[0];
+
+  if (!subId) {
+    return undefined;
+  }
+
+  const sub = await stripeCli.subscriptions.retrieve(subId, {
+    expand: ["items.data.price.tiers"],
+  });
+
+  return sub;
+};
+
 export const paramsToCurSub = async ({
   attachParams,
 }: {
diff --git a/server/src/internal/customers/attach/mergeUtils/mergeNewSubItems.ts b/server/src/internal/customers/attach/mergeUtils/mergeNewSubItems.ts
new file mode 100644
index 000000000..e0c42a1d6
--- /dev/null
+++ b/server/src/internal/customers/attach/mergeUtils/mergeNewSubItems.ts
@@ -0,0 +1,43 @@
+import { isArrearPrice } from "@/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.js";
+import { ItemSet } from "@/utils/models/ItemSet.js";
+import Stripe from "stripe";
+
+export const mergeNewSubItems = ({
+  itemSet,
+  curSubItems,
+}: {
+  itemSet: ItemSet;
+  curSubItems: Stripe.SubscriptionItem[];
+}) => {
+  // 1. Don't need to add arrear prices if they already exist...
+  let newSubItems = structuredClone(itemSet.subItems);
+  const newArrearSubItems: any[] = [];
+
+  newSubItems = newSubItems.filter((newSi) => {
+    const existingItem = curSubItems.find((si) => si.price?.id === newSi.price);
+    if (isArrearPrice({ price: newSi.autumnPrice }) && existingItem) {
+      newArrearSubItems.push(newSi);
+      return false;
+    }
+    return true;
+  });
+
+  // 2. Add new subItems
+  for (let i = 0; i < newSubItems.length; i++) {
+    const newItem = newSubItems[i];
+    const existingItem = curSubItems.find(
+      (si) => si.price?.id === newItem.price
+    );
+
+    if (!existingItem) continue;
+
+    newSubItems[i] = {
+      id: existingItem.id,
+      quantity: (existingItem.quantity || 0) + (newItem.quantity || 0),
+      // price: newItem.price,
+      // autumnPrice: newItem.autumnPrice,
+    };
+  }
+
+  return newSubItems;
+};
diff --git a/server/src/internal/customers/attach/mergeUtils/paramsToSubItems.ts b/server/src/internal/customers/attach/mergeUtils/paramsToSubItems.ts
new file mode 100644
index 000000000..6bcef40d4
--- /dev/null
+++ b/server/src/internal/customers/attach/mergeUtils/paramsToSubItems.ts
@@ -0,0 +1,177 @@
+import Stripe from "stripe";
+import { AttachParams } from "../../cusProducts/AttachParams.js";
+import { getStripeSubItems2 } from "@/external/stripe/stripeSubUtils/getStripeSubItems.js";
+import { AttachConfig, FullCusProduct } from "@autumn/shared";
+import { attachParamToCusProducts } from "../attachUtils/convertAttachParams.js";
+import { getExistingCusProducts } from "../../cusProducts/cusProductUtils/getExistingCusProducts.js";
+
+import { ExtendedRequest } from "@/utils/models/Request.js";
+import { cusProductToPrices } from "../../cusProducts/cusProductUtils/convertCusProduct.js";
+import {
+  isArrearPrice,
+  isUsagePrice,
+} from "@/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.js";
+import {
+  findStripeItemForPrice,
+  subItemInCusProduct,
+} from "@/external/stripe/stripeSubUtils/stripeSubItemUtils.js";
+import { mergeNewSubItems } from "./mergeNewSubItems.js";
+import { formatPrice } from "@/internal/products/prices/priceUtils.js";
+
+const getCusProductsToRemove = ({
+  attachParams,
+}: {
+  attachParams: AttachParams;
+}) => {
+  const products = attachParams.products;
+  const cusProducts = attachParams.cusProducts;
+
+  const cusProductsToRemove: FullCusProduct[] = [];
+  for (const product of products) {
+    // Get cur main and cur same
+    const { curMainProduct, curSameProduct } = getExistingCusProducts({
+      product,
+      cusProducts: attachParams.cusProducts,
+      internalEntityId: attachParams.internalEntityId,
+    });
+
+    // 1. If product is an add on, and there's current same, add it
+    if (product.is_add_on && curSameProduct) {
+      cusProductsToRemove.push(curSameProduct);
+    }
+
+    // 2. If product is a main product, add curMain
+    if (curMainProduct) {
+      cusProductsToRemove.push(curMainProduct);
+    }
+  }
+
+  // Get unique cus products, by cusProduct.id
+  const uniqueCusProductsToRemove = cusProductsToRemove.filter(
+    (cusProduct, index, array) =>
+      array.findIndex((cp) => cp.id === cusProduct.id) === index
+  );
+
+  return uniqueCusProductsToRemove;
+};
+
+export const paramsToSubItems = async ({
+  req,
+  sub,
+  attachParams,
+  config,
+}: {
+  req: ExtendedRequest;
+  sub: Stripe.Subscription;
+  attachParams: AttachParams;
+  config: AttachConfig;
+}) => {
+  const { logger } = req;
+  const curSubItems = sub.items.data;
+  const itemSet = await getStripeSubItems2({
+    attachParams,
+    config,
+  });
+
+  // 1. Remove items related to cur cus product...
+  const cusProductsToRemove = getCusProductsToRemove({ attachParams });
+
+  const newSubItems = mergeNewSubItems({
+    itemSet,
+    curSubItems,
+  });
+
+  const allCusProducts = attachParams.customer.customer_products;
+
+  console.log(
+    `REMOVING CUS PRODUCTS:`,
+    cusProductsToRemove.map((cp) => `${cp.product.id}`)
+  );
+
+  // 3. Remove items related to cus products to remove
+  for (const cusProduct of cusProductsToRemove) {
+    const prices = cusProductToPrices({ cusProduct });
+    // console.log(
+    //   `Prices:`,
+    //   prices.map((p) => formatPrice({ price: p }))
+    // );
+    for (const price of prices) {
+      const existingSubItem = findStripeItemForPrice({
+        price,
+        stripeItems: curSubItems,
+        stripeProdId: cusProduct.product.processor?.id,
+      });
+
+      if (!existingSubItem) continue;
+
+      // 1. If arrear price
+      if (isArrearPrice({ price })) {
+        if (
+          allCusProducts.some((cp) => {
+            if (cp.id === cusProduct.id) return false;
+
+            return subItemInCusProduct({
+              cusProduct: cp,
+              subItem: existingSubItem as Stripe.SubscriptionItem,
+            });
+          })
+        ) {
+          continue;
+        }
+
+        if (
+          itemSet.subItems.some((si) => si.price == existingSubItem.price?.id)
+        ) {
+          continue;
+        }
+
+        newSubItems.push({
+          id: existingSubItem.id,
+          deleted: true,
+        });
+
+        continue;
+      }
+
+      // Helper function to handle quantity updates and deletion
+      const updateItemQuantity = (item: any, newQuantity: number) => {
+        if (newQuantity <= 0) {
+          item.deleted = true;
+          item.quantity = undefined;
+        } else {
+          item.quantity = newQuantity;
+        }
+      };
+
+      // 1. Get quantity to remove
+      const quantityToRemove = 1;
+
+      // 2. Check if item already exists in newSubItems
+      const existingItemIndex = newSubItems.findIndex(
+        (si) => si.id === existingSubItem.id
+      );
+
+      if (existingItemIndex !== -1) {
+        // Update existing item in newSubItems
+        const currentQuantity = newSubItems[existingItemIndex].quantity || 0;
+        const newQuantity = currentQuantity - quantityToRemove;
+        updateItemQuantity(newSubItems[existingItemIndex], newQuantity);
+      } else {
+        // Add new item to newSubItems
+        const currentQuantity = existingSubItem.quantity || 0;
+        const newQuantity = currentQuantity - quantityToRemove;
+        newSubItems.push({
+          id: existingSubItem.id,
+          quantity: newQuantity,
+        });
+        updateItemQuantity(newSubItems[newSubItems.length - 1], newQuantity);
+      }
+    }
+  }
+
+  return {
+    subItems: newSubItems,
+    invoiceItems: itemSet.invoiceItems,
+    usageFeatures: itemSet.usageFeatures,
+  };
+};
diff --git a/server/src/internal/customers/attach/unifiedAttach/createUpgradeProrationItems.ts b/server/src/internal/customers/attach/unifiedAttach/createUpgradeProrationItems.ts
deleted file mode 100644
index 0b24f1c37..000000000
--- a/server/src/internal/customers/attach/unifiedAttach/createUpgradeProrationItems.ts
+++ /dev/null
@@ -1,90 +0,0 @@
-import { ExtendedRequest } from "@/utils/models/Request.js";
-import { AttachParams } from "../../cusProducts/AttachParams.js";
-import { AttachConfig, intervalsSame } from "@autumn/shared";
-import { subToAutumnInterval } from "@/external/stripe/utils.js";
-import Stripe from "stripe";
-import { ItemSet } from "@/utils/models/ItemSet.js";
-import { attachParamsToCurCusProduct } from "../attachUtils/convertAttachParams.js";
-
-// 1. Create proration items for fixed prices
-const createFixedPriceProrations = async ({
-  req,
-  attachParams,
-  config,
-  currentSubs,
-  itemSets,
-}: {
-  req: ExtendedRequest;
-  attachParams: AttachParams;
-  currentSubs: Stripe.Subscription[];
-  config: AttachConfig;
-  itemSets: ItemSet[];
-}) => {
-  const { stripeCli } = attachParams;
-  const curCusProduct = attachParamsToCurCusProduct({ attachParams });
-
-  for (const sub of currentSubs) {
-    const itemSet = itemSets.find((itemSet) =>
-      intervalsSame({
-        intervalA: itemSet,
-        intervalB: subToAutumnInterval(sub),
-      })
-    );
-
-    // const { newItems, shouldCancel } = mergeWithCurItems({
-    //   sub,
-    //   itemSet,
-    //   curCusProduct,
-    // });
-    // subToNewItems.push({
-    //   sub,
-    //   newItems,
-    //   shouldCancel,
-    // });
-
-    // if (newItems.length == 0) continue;
-    // if (shouldCancel) {
-    //   const preview = await stripeCli.invoices.createPreview({
-    //     subscription: sub.id,
-    //     subscription_details: {
-    //       cancel_now: true,
-    //     },
-    //   });
-    //   for (const lineItem of preview.lines.data) {
-    //     await stripeCli.invoiceItems.create({
-    //       customer: attachParams.customer.processor.id,
-    //       amount: lineItem.amount,
-    //       currency: lineItem.currency,
-    //       description: lineItem.description || "",
-    //     });
-    //   }
-    // } else {
-    //   const [originalPreview, previewInvoice] = await Promise.all([
-    //     stripeCli.invoices.createPreview({
-    //       subscription: sub.id,
-    //     }),
-    //     stripeCli.invoices.createPreview({
-    //       subscription: sub.id,
-    //       subscription_details: {
-    //         items: newItems,
-    //       },
-    //     }),
-    //   ]);
-    //   for (const lineItem of previewInvoice.lines.data) {
-    //     const inCurItems = originalPreview.lines.data.find(
-    //       (i) => i.id == lineItem.id
-    //     );
-    //     if (!inCurItems) {
-    //       // console.log(lineItem.description, lineItem.amount);
-    //       // prorationItems.push();
-    //       await stripeCli.invoiceItems.create({
-    //         customer: attachParams.customer.processor.id,
-    //         amount: lineItem.amount,
-    //         currency: lineItem.currency,
-    //         description: lineItem.description || "",
-    //       });
-    //     }
-    //   }
-    // }
-  }
-};
diff --git a/server/src/internal/customers/attach/unifiedAttach/handleUnifiedAttach.ts b/server/src/internal/customers/attach/unifiedAttach/handleUnifiedAttach.ts
deleted file mode 100644
index 6c5742eea..000000000
--- a/server/src/internal/customers/attach/unifiedAttach/handleUnifiedAttach.ts
+++ /dev/null
@@ -1,302 +0,0 @@
-// import Stripe from "stripe";
-// import { DrizzleCli } from "@/db/initDrizzle.js";
-// import { createStripeSub } from "@/external/stripe/stripeSubUtils/createStripeSub.js";
-// import { AttachParams } from "@/internal/customers/cusProducts/AttachParams.js";
-// import { freeTrialToStripeTimestamp } from "@/internal/products/free-trials/freeTrialUtils.js";
-// import {
-//   AttachConfig,
-//   FullCusProduct,
-//   intervalsSame,
-//   ProrationBehavior,
-// } from "@autumn/shared";
-// import { getStripeSubItems } from "@/external/stripe/stripeSubUtils/getStripeSubItems.js";
-// import { ExtendedRequest } from "@/utils/models/Request.js";
-
-// export const handleUnifiedAttach = async ({
-//   req,
-//   attachParams,
-//   config,
-// }: {
-//   req: ExtendedRequest;
-//   attachParams: AttachParams;
-//   config: AttachConfig;
-// }) => {
-//   // 1. Get upcoming item sets, and current subscriptions
-//   const itemSets = await getStripeSubItems({
-//     attachParams,
-//     carryExistingUsages: config.carryUsage,
-//   });
-
-//   const currentSubs = await getCurrentSubs({
-//     db: req.db,
-//     attachParams,
-//   });
-
-//   // 2. Create invoice items for prorations
-// };
-
-// Expire old cus product
-// Create new full cus product
-// Insert new invoices
-
-// export const updateSubsDiffInt = async ({
-//   req,
-//   stripeCli,
-//   curCusProduct,
-//   attachParams,
-//   stripeSubs,
-//   config,
-// }: {
-//   req: ExtendedRequest;
-//   stripeCli: Stripe;
-//   curCusProduct: FullCusProduct;
-//   attachParams: AttachParams;
-//   stripeSubs: Stripe.Subscription[];
-//   config: AttachConfig;
-// }) => {
-//   const { db, logger } = req;
-//   const itemSets = await getStripeSubItems({
-//     attachParams,
-//     carryExistingUsages: config.carryUsage,
-//   });
-
-//   // let trialEnd = config.disableTrial
-//   //   ? undefined
-//   //   : freeTrialToStripeTimestamp({
-//   //       freeTrial: attachParams.freeTrial,
-//   //       now: attachParams.now,
-//   //     });
-
-//   // 1. Create prorations for fixed price items
-//   const subToNewItems: any = [];
-
-//   for (const sub of stripeSubs) {
-//     const itemSet = itemSets.find((itemSet) =>
-//       intervalsSame({
-//         intervalA: itemSet,
-//         intervalB: subToAutumnInterval(sub),
-//       })
-//     );
-
-//     const { newItems, shouldCancel } = mergeWithCurItems({
-//       sub,
-//       itemSet,
-//       curCusProduct,
-//     });
-
-//     subToNewItems.push({
-//       sub,
-//       newItems,
-//       shouldCancel,
-//     });
-
-//     if (newItems.length == 0) continue;
-
-//     if (shouldCancel) {
-//       const preview = await stripeCli.invoices.createPreview({
-//         subscription: sub.id,
-//         subscription_details: {
-//           cancel_now: true,
-//         },
-//       });
-
-//       for (const lineItem of preview.lines.data) {
-//         await stripeCli.invoiceItems.create({
-//           customer: attachParams.customer.processor.id,
-//           amount: lineItem.amount,
-//           currency: lineItem.currency,
-//           description: lineItem.description || "",
-//         });
-//       }
-//     } else {
-//       const [originalPreview, previewInvoice] = await Promise.all([
-//         stripeCli.invoices.createPreview({
-//           subscription: sub.id,
-//         }),
-//         stripeCli.invoices.createPreview({
-//           subscription: sub.id,
-//           subscription_details: {
-//             items: newItems,
-//           },
-//         }),
-//       ]);
-
-//       for (const lineItem of previewInvoice.lines.data) {
-//         const inCurItems = originalPreview.lines.data.find(
-//           (i) => i.id == lineItem.id
-//         );
-
-//         if (!inCurItems) {
-//           // console.log(lineItem.description, lineItem.amount);
-//           // prorationItems.push();
-//           await stripeCli.invoiceItems.create({
-//             customer: attachParams.customer.processor.id,
-//             amount: lineItem.amount,
-//             currency: lineItem.currency,
-//             description: lineItem.description || "",
-//           });
-//         }
-//       }
-//     }
-//   }
-
-//   for (const subToNewItem of subToNewItems) {
-//     console.log(`Sub to new item`);
-//     console.log(`Sub ID: ${subToNewItem.sub.id}`);
-//     console.log(`New items: ${JSON.stringify(subToNewItem.newItems)}`);
-//     console.log(`Should cancel: ${subToNewItem.shouldCancel}`);
-//     console.log(`--------------------------------`);
-//   }
-//   throw new Error("Stop");
-
-//   // 2. Create prorations for single use items
-//   let { invoiceItems, cusEntIds } = await createUsageInvoiceItems({
-//     db,
-//     attachParams,
-//     cusProduct: curCusProduct,
-//     stripeSubs,
-//     logger,
-//   });
-
-//   // Create any new subs
-//   const createItemSets = itemSets.filter((itemSet) => {
-//     return !stripeSubs.some((sub) =>
-//       intervalsSame({
-//         intervalA: itemSet,
-//         intervalB: subToAutumnInterval(sub),
-//       })
-//     );
-//   });
-
-//   const updatedSubs = [];
-//   const invoices = [];
-
-//   // 1. Create new subscriptions
-//   for (const itemSet of createItemSets) {
-//     const newSub = await createStripeSub({
-//       db,
-//       attachParams,
-//       itemSet,
-//     });
-
-//     updatedSubs.push(newSub);
-//     invoices.push(newSub.latest_invoice as Stripe.Invoice);
-//   }
-
-//   // 2. Update or cancel old subs
-//   for (const newItemSet of subToNewItems) {
-//     if (newItemSet.shouldCancel) {
-//       await stripeCli.subscriptions.cancel(newItemSet.sub.id, {
-//         prorate: false,
-//         cancellation_details: {
-//           comment: "autumn_upgrade",
-//         },
-//       });
-//     } else {
-//       const intervalConfig = subToAutumnInterval(newItemSet.sub);
-//       const { updatedSub, latestInvoice } = await updateStripeSub({
-//         req,
-//         attachParams,
-//         config: {
-//           ...config,
-//           proration: ProrationBehavior.None,
-//         },
-//         stripeSubs: [newItemSet.sub],
-//         itemSet: {
-//           items: newItemSet.newItems,
-//           interval: intervalConfig.interval,
-//           intervalCount: intervalConfig.intervalCount,
-//         } as any,
-//         intervalConfig: subToAutumnInterval(newItemSet.sub),
-//       });
-
-//       updatedSubs.push(updatedSub!);
-//       if (latestInvoice) {
-//         invoices.push(latestInvoice);
-//       }
-//     }
-//   }
-
-//   return {
-//     newSubs: stripeSubs,
-//     invoices,
-//     // invoice: latestInvoice,
-//     // newInvoiceIds,
-//   };
-// };
-
-// 2. Update / cancel old subscriptions
-
-// // 3. Update current subscription
-// logger.info("1.2: Updating current subscription");
-// const { updatedSub, latestInvoice } = await updateStripeSub({
-//   req,
-//   attachParams,
-//   config,
-//   trialEnd,
-//   itemSet: firstItemSet,
-//   stripeSubs: [firstSub],
-// });
-
-// await resetUsageBalances({
-//   db,
-//   cusEntIds,
-//   cusProduct: curCusProduct,
-// });
-
-// let newSubs = [updatedSub!];
-// const newInvoiceIds = latestInvoice ? [latestInvoice.id] : [];
-
-// // 4. Update current sub schedules if exist...
-// logger.info("1.3 Updating current sub schedules");
-// await updateCurSchedules({
-//   db,
-//   stripeCli,
-//   curCusProduct,
-//   attachParams,
-//   itemSets,
-//   logger,
-// });
-
-// // 5. Cancel other subscriptions
-// for (const sub of stripeSubs.slice(1)) {
-//   logger.info(`1.4: canceling additional sub: ${sub.id}`);
-
-//   // Filter out
-//   await stripeCli.subscriptions.cancel(sub.id, {
-//     prorate: true,
-//     cancellation_details: {
-//       comment: "autumn_upgrade",
-//     },
-//   });
-// }
-
-// // 6. Create subs for other intervals
-// for (const itemSet of itemSets.slice(1)) {
-//   const newSub = await createStripeSub({
-//     db,
-//     stripeCli,
-//     customer: attachParams.customer,
-//     org: attachParams.org,
-//     itemSet,
-//     invoiceOnly: attachParams.invoiceOnly || false,
-//     freeTrial: attachParams.freeTrial,
-//     // anchorToUnix: updatedSub!.current_period_end! * 1000,
-//     now: attachParams.now,
-//   });
-
-//   newSubs.push(newSub);
-//   const latestInvoice = newSub.latest_invoice as Stripe.Invoice;
-//   newInvoiceIds.push(latestInvoice.id);
-// }
-
-// const firstSub = stripeSubs?.[0];
-// const firstItemSet = itemSets?.[0];
-
-// await addSubItemsToRemove({
-//   sub: firstSub,
-//   cusProduct: curCusProduct,
-//   itemSet: firstItemSet,
-// });
-
-// throw new Error("Stop");
diff --git a/server/src/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.ts b/server/src/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.ts
index 8404e5962..9e0f93823 100644
--- a/server/src/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.ts
+++ b/server/src/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.ts
@@ -40,6 +40,12 @@ export const isUsagePrice = ({
   return isUsage;
 };
 
+export const isArrearPrice = ({ price }: { price?: Price }) => {
+  if (!price) return false;
+  let billingType = getBillingType(price.config);
+  return billingType == BillingType.UsageInArrear;
+};
+
 export const isPrepaidPrice = ({ price }: { price: Price }) => {
   let billingType = getBillingType(price.config);
   return billingType == BillingType.UsageInAdvance;
diff --git a/server/src/utils/models/ItemSet.ts b/server/src/utils/models/ItemSet.ts
index 99895b8ea..4fbf55886 100644
--- a/server/src/utils/models/ItemSet.ts
+++ b/server/src/utils/models/ItemSet.ts
@@ -1,13 +1,30 @@
-import { BillingInterval } from "@autumn/shared";
+import { BillingInterval, Price } from "@autumn/shared";
+import Stripe from "stripe";
 import { z } from "zod";
 
-export const ItemSetSchema = z.object({
-  items: z.array(z.any()),
-  prices: z.array(z.any()),
-  interval: z.nativeEnum(BillingInterval),
-  intervalCount: z.number(),
-  subMeta: z.record(z.string(), z.any()),
-  usageFeatures: z.array(z.string()),
-});
+// export const ItemSetSchema = z.object({
+//   items: z.array(z.any()),
+//   prices: z.array(z.any()),
+//   interval: z.nativeEnum(BillingInterval),
+//   intervalCount: z.number(),
+//   subMeta: z.record(z.string(), z.any()),
+//   usageFeatures: z.array(z.string()),
+// });
 
-export type ItemSet = z.infer<typeof ItemSetSchema>;
+// export type ItemSet = z.infer<typeof ItemSetSchema>;
+
+export type ItemSet = {
+  subItems: (Stripe.SubscriptionUpdateParams.Item & {
+    autumnPrice?: Price;
+  })[];
+  invoiceItems: Stripe.SubscriptionUpdateParams.AddInvoiceItem[];
+  usageFeatures: string[];
+};
+
+// export const ItemSetSchema2 = z.object({
+//   subItems: z.array(z.any()),
+//   invoiceItems: z.array(z.any()),
+//   usageFeatures: z.array(z.any()),
+// });
+
+// export type ItemSet2 = z.infer<typeof ItemSetSchema2>;
diff --git a/server/tests/merged/mergeUtils.test.ts b/server/tests/merged/mergeUtils.test.ts
new file mode 100644
index 000000000..291b5ec83
--- /dev/null
+++ b/server/tests/merged/mergeUtils.test.ts
@@ -0,0 +1,22 @@
+import { cusProductToPrices } from "@/internal/customers/cusProducts/cusProductUtils/convertCusProduct.js";
+import { isFixedPrice } from "@/internal/products/prices/priceUtils/usagePriceUtils/classifyUsagePrice.js";
+import { FullCusProduct } from "@autumn/shared";
+
+export const cusProductToSubIds = ({
+  cusProducts,
+}: {
+  cusProducts: FullCusProduct[];
+}) => {
+  return [...new Set(cusProducts.flatMap((cp) => cp.subscription_ids || []))];
+};
+
+export const cpToPrice = ({
+  cp,
+  type,
+}: {
+  cp: FullCusProduct;
+  type: "base" | "arrear" | "cont" | "prepaid";
+}) => {
+  const prices = cusProductToPrices({ cusProduct: cp });
+  return prices.find((p) => isFixedPrice({ price: p }));
+};
diff --git a/server/tests/merged/mergedAdd1.ts b/server/tests/merged/mergedAdd1.ts
new file mode 100644
index 000000000..e412f131f
--- /dev/null
+++ b/server/tests/merged/mergedAdd1.ts
@@ -0,0 +1,185 @@
+import chalk from "chalk";
+import { setupBefore } from "tests/before.js";
+import { Stripe } from "stripe";
+import { createProducts } from "tests/utils/productUtils.js";
+import { constructProduct } from "@/utils/scriptUtils/createTestProducts.js";
+import { TestFeature } from "tests/setup/v2Features.js";
+import { AutumnInt } from "@/external/autumn/autumnCli.js";
+import { initCustomer } from "@/utils/scriptUtils/initCustomer.js";
+import { APIVersion, AppEnv, entities, Organization } from "@autumn/shared";
+import { constructArrearItem } from "@/utils/scriptUtils/constructItem.js";
+import { DrizzleCli } from "@/db/initDrizzle.js";
+import { addPrefixToProducts } from "tests/utils/testProductUtils/testProductUtils.js";
+import { CusService } from "@/internal/customers/CusService.js";
+import { expect } from "chai";
+import { cpToPrice, cusProductToSubIds } from "./mergeUtils.test.js";
+import { findStripeItemForPrice } from "@/external/stripe/stripeSubUtils/stripeSubItemUtils.js";
+
+// UNCOMMENT FROM HERE
+let pro = constructProduct({
+  id: "pro",
+  items: [constructArrearItem({ featureId: TestFeature.Words })],
+  type: "pro",
+});
+
+describe(`${chalk.yellowBright("mergedAdd1: Testing merged subs, with track")}`, () => {
+  let customerId = "mergedAdd1";
+  let autumn: AutumnInt = new AutumnInt({ version: APIVersion.v1_4 });
+
+  let stripeCli: Stripe;
+  let testClockId: string;
+  let curUnix: number;
+  let db: DrizzleCli;
+  let org: Organization;
+  let env: AppEnv;
+
+  before(async function () {
+    await setupBefore(this);
+    const { autumnJs } = this;
+    db = this.db;
+    org = this.org;
+    env = this.env;
+
+    stripeCli = this.stripeCli;
+
+    addPrefixToProducts({
+      products: [pro],
+      prefix: customerId,
+    });
+
+    await createProducts({
+      autumn: autumnJs,
+      products: [pro],
+      db,
+      orgId: org.id,
+      env,
+      customerId,
+    });
+
+    const { testClockId: testClockId1 } = await initCustomer({
+      autumn: autumnJs,
+      customerId,
+      db,
+      org,
+      env,
+      attachPm: "success",
+    });
+
+    testClockId = testClockId1!;
+  });
+
+  const entities = [
+    {
+      id: "1",
+      name: "Entity 1",
+      feature_id: TestFeature.Users,
+    },
+    {
+      id: "2",
+      name: "Entity 2",
+      feature_id: TestFeature.Users,
+    },
+  ];
+
+  it("should attach pro product", async function () {
+    await autumn.entities.create(customerId, entities);
+
+    await autumn.attach({
+      customer_id: customerId,
+      product_id: pro.id,
+      entity_id: "1",
+    });
+
+    await autumn.attach({
+      customer_id: customerId,
+      product_id: pro.id,
+      entity_id: "2",
+    });
+
+    // 1. Should have one sub
+    const fullCus = await CusService.getFull({
+      db,
+      idOrInternalId: customerId,
+      orgId: org.id,
+      env,
+    });
+
+    const cusProducts = fullCus.customer_products;
+    expect(cusProducts.length).to.equal(3);
+
+    const subIds = cusProductToSubIds({ cusProducts });
+    expect(subIds.length).to.equal(1);
+
+    // Get sub
+    const sub = await stripeCli.subscriptions.retrieve(subIds[0]);
+
+    // 1. Should have quantity 2 for base price
+    const basePrice = cpToPrice({ cp: cusProducts[0], type: "base" });
+    const arrearPrice = cpToPrice({ cp: cusProducts[0], type: "arrear" });
+
+    const baseItem = findStripeItemForPrice({
+      price: basePrice!,
+      stripeItems: sub.items.data,
+    })!;
+
+    const arrearItem = findStripeItemForPrice({
+      price: arrearPrice!,
+      stripeItems: sub.items.data,
+    })!;
+
+    expect(baseItem.quantity).to.equal(2);
+    expect(arrearItem.quantity).to.equal(0);
+  });
+
+  // it("should attach premium product", async function () {
+  //   const wordsUsage = 100000;
+  //   await autumn.track({
+  //     customer_id: customerId,
+  //     feature_id: TestFeature.Words,
+  //     value: wordsUsage,
+  //   });
+
+  //   curUnix = await advanceTestClock({
+  //     stripeCli,
+  //     testClockId,
+  //     advanceTo: addWeeks(new Date(), 2).getTime(),
+  //     waitForSeconds: 10,
+  //   });
+
+  //   await attachAndExpectCorrect({
+  //     autumn,
+  //     customerId,
+  //     product: premium,
+  //     stripeCli,
+  //     db,
+  //     org,
+  //     env,
+  //   });
+  // });
+
+  // it("should attach growth product", async function () {
+  //   const wordsUsage = 200000;
+  //   await autumn.track({
+  //     customer_id: customerId,
+  //     feature_id: TestFeature.Words,
+  //     value: wordsUsage,
+  //   });
+
+  //   curUnix = await advanceTestClock({
+  //     stripeCli,
+  //     testClockId,
+  //     advanceTo: addWeeks(curUnix, 1).getTime(),
+  //     waitForSeconds: 10,
+  //   });
+
+  //   await attachAndExpectCorrect({
+  //     autumn,
+  //     customerId,
+  //     product: growth,
+  //     stripeCli,
+  //     db,
+  //     org,
+  //     env,
+  //   });
+  // });
+});