diff --git a/packages/stitcher/src/interstitials.ts b/packages/stitcher/src/interstitials.ts
index 5c3ae144..260a5509 100644
--- a/packages/stitcher/src/interstitials.ts
+++ b/packages/stitcher/src/interstitials.ts
@@ -45,25 +45,30 @@ export function getStaticDateRanges(session: Session, isLive: boolean) {
 }
 
 export async function getAssets(session: Session, dateTime: DateTime) {
-  const assets: InterstitialAsset[] = [];
-
   const interstitial = session.interstitials.find((interstitial) =>
     interstitial.dateTime.equals(dateTime),
   );
 
-  if (interstitial?.vast) {
-    const nextAssets = await getAssetsFromVast(interstitial.vast);
-    assets.push(...nextAssets);
+  if (!interstitial) {
+    return [];
   }
 
-  if (interstitial?.assets) {
-    assets.push(...interstitial.assets);
+  const assets: InterstitialAsset[] = [];
+
+  for (const chunk of interstitial.chunks) {
+    if (chunk.type === "vast") {
+      const nextAssets = await getAssetsFromVast(chunk.data);
+      assets.push(...nextAssets);
+    }
+    if (chunk.type === "asset") {
+      assets.push(chunk.data);
+    }
   }
 
   return assets;
 }
 
-export function appendInterstitials(
+export function mergeInterstitials(
   source: Interstitial[],
   interstitials: Interstitial[],
 ) {
@@ -74,31 +79,22 @@ export function appendInterstitials(
 
     if (!target) {
       source.push(interstitial);
-      continue;
-    }
-
-    if (interstitial.assets) {
-      if (!target.assets) {
-        target.assets = interstitial.assets;
-      } else {
-        target.assets.push(...interstitial.assets);
-      }
-    }
-
-    if (interstitial.vast) {
-      target.vast = interstitial.vast;
-    }
-
-    if (interstitial.assetList) {
-      target.assetList = interstitial.assetList;
+    } else {
+      // If we found a source for the particular dateTime, we push the
+      // other chunks at the end.
+      target.chunks.push(...interstitial.chunks);
     }
   }
 }
 
 function getAssetListUrl(interstitial: Interstitial, session?: Session) {
-  if (interstitial.assetList) {
-    return interstitial.assetList.url;
+  const assetListChunks = interstitial.chunks.filter(
+    (chunk) => chunk.type === "assetList",
+  );
+  if (assetListChunks.length === 1 && assetListChunks[0]) {
+    return assetListChunks[0].data.url;
   }
+
   return createUrl("out/asset-list.json", {
     dt: interstitial.dateTime.toISO(),
     sid: session?.id,
@@ -106,17 +102,13 @@ function getAssetListUrl(interstitial: Interstitial, session?: Session) {
 }
 
 function getTimelineStyle(interstitial: Interstitial) {
-  if (interstitial.assets) {
-    for (const asset of interstitial.assets) {
-      if (asset.kind === "ad") {
-        return "HIGHLIGHT";
-      }
+  for (const chunk of interstitial.chunks) {
+    if (chunk.type === "asset" && chunk.data.kind === "ad") {
+      return "HIGHLIGHT";
+    }
+    if (chunk.type === "vast") {
+      return "HIGHLIGHT";
     }
   }
-
-  if (interstitial.vast) {
-    return "HIGHLIGHT";
-  }
-
   return "PRIMARY";
 }
diff --git a/packages/stitcher/src/playlist.ts b/packages/stitcher/src/playlist.ts
index 423f7ecf..9c5a11ae 100644
--- a/packages/stitcher/src/playlist.ts
+++ b/packages/stitcher/src/playlist.ts
@@ -1,9 +1,9 @@
 import { assert } from "shared/assert";
 import { filterMasterPlaylist, formatFilterToQueryParam } from "./filters";
 import {
-  appendInterstitials,
   getAssets,
   getStaticDateRanges,
+  mergeInterstitials,
 } from "./interstitials";
 import { encrypt } from "./lib/crypto";
 import { createUrl, joinUrl, resolveUri } from "./lib/url";
@@ -202,7 +202,7 @@ async function initSessionOnMasterReq(session: Session) {
       session,
       vmap.adBreaks,
     );
-    appendInterstitials(session.interstitials, interstitials);
+    mergeInterstitials(session.interstitials, interstitials);
 
     storeSession = true;
   }
@@ -229,10 +229,14 @@ export function mapAdBreaksToSessionInterstitials(
 
     interstitials.push({
       dateTime,
-      vast: {
-        url: adBreak.vastUrl,
-        data: adBreak.vastData,
-      },
+      // We're going to push a single chunk here and have them merged before
+      // we return the full list of interstitials.
+      chunks: [
+        {
+          type: "vast",
+          data: { url: adBreak.vastUrl, data: adBreak.vastData },
+        },
+      ],
     });
   }
 
diff --git a/packages/stitcher/src/session.ts b/packages/stitcher/src/session.ts
index 2236278d..86610146 100644
--- a/packages/stitcher/src/session.ts
+++ b/packages/stitcher/src/session.ts
@@ -1,10 +1,10 @@
 import { randomUUID } from "crypto";
 import { DateTime } from "luxon";
 import { kv } from "./adapters/kv";
-import { appendInterstitials } from "./interstitials";
+import { mergeInterstitials } from "./interstitials";
 import { JSON } from "./lib/json";
 import { resolveUri } from "./lib/url";
-import type { Interstitial } from "./types";
+import type { Interstitial, InterstitialChunk } from "./types";
 import type { VmapParams } from "./vmap";
 
 export interface Session {
@@ -57,7 +57,7 @@ export async function createSession(params: {
       startTime,
       params.interstitials,
     );
-    appendInterstitials(session.interstitials, interstitials);
+    mergeInterstitials(session.interstitials, interstitials);
   }
 
   const value = JSON.stringify(session);
@@ -83,21 +83,43 @@ function mapSessionInterstitials(
   startTime: DateTime,
   interstitials: SessionInterstitial[],
 ) {
-  return interstitials.map<Interstitial>((item) => {
-    const { time, duration, assets, ...rest } = item;
+  const result: Interstitial[] = [];
+
+  for (const interstitial of interstitials) {
     const dateTime =
-      typeof time === "string"
-        ? DateTime.fromISO(time)
-        : startTime.plus({ seconds: time });
+      typeof interstitial.time === "string"
+        ? DateTime.fromISO(interstitial.time)
+        : startTime.plus({ seconds: interstitial.time });
 
-    return {
-      dateTime,
-      duration,
-      assets: assets?.map((asset) => {
+    const chunks: InterstitialChunk[] = [];
+
+    if (interstitial.assets) {
+      for (const asset of interstitial.assets) {
         const { uri, ...rest } = asset;
-        return { url: resolveUri(uri), ...rest };
-      }),
-      ...rest,
-    };
-  });
+        chunks.push({
+          type: "asset",
+          data: {
+            url: resolveUri(uri),
+            ...rest,
+          },
+        });
+      }
+    }
+
+    if (interstitial.vast) {
+      chunks.push({ type: "vast", data: interstitial.vast });
+    }
+
+    if (interstitial.assetList) {
+      chunks.push({ type: "assetList", data: interstitial.assetList });
+    }
+
+    result.push({
+      dateTime,
+      duration: interstitial.duration,
+      chunks,
+    });
+  }
+
+  return result;
 }
diff --git a/packages/stitcher/src/types.ts b/packages/stitcher/src/types.ts
index 44490888..9fb50a68 100644
--- a/packages/stitcher/src/types.ts
+++ b/packages/stitcher/src/types.ts
@@ -15,10 +15,13 @@ export interface InterstitialAssetList {
   url: string;
 }
 
+export type InterstitialChunk =
+  | { type: "asset"; data: InterstitialAsset }
+  | { type: "vast"; data: InterstitialVast }
+  | { type: "assetList"; data: InterstitialAssetList };
+
 export interface Interstitial {
   dateTime: DateTime;
   duration?: number;
-  assets?: InterstitialAsset[];
-  vast?: InterstitialVast;
-  assetList?: InterstitialAssetList;
+  chunks: InterstitialChunk[];
 }