diff --git a/packages/stitcher/src/interstitials.ts b/packages/stitcher/src/interstitials.ts
index de227a97..96ddd258 100644
--- a/packages/stitcher/src/interstitials.ts
+++ b/packages/stitcher/src/interstitials.ts
@@ -1,26 +1,21 @@
-import { DateTime } from "luxon";
 import { createUrl } from "./lib/url";
 import { getAssetsFromVast } from "./vast";
 import type { DateRange } from "./parser";
 import type { Session } from "./session";
 import type { Interstitial, InterstitialAsset } from "./types";
+import type { DateTime } from "luxon";
 
 export function getStaticDateRanges(session: Session, isLive: boolean) {
-  const group = getGroupedInterstitials(session.interstitials);
-
-  const dateRanges: DateRange[] = [];
-
-  for (const [ts, interstitials] of group.entries()) {
-    const startDate = DateTime.fromMillis(ts);
-
-    const assetListUrl = getAssetListUrl(startDate, interstitials, session);
+  return session.interstitials.map<DateRange>((interstitial) => {
+    const startDate = interstitial.dateTime;
+    const assetListUrl = getAssetListUrl(interstitial, session);
 
     const clientAttributes: Record<string, number | string> = {
       RESTRICT: "SKIP,JUMP",
       "ASSET-LIST": assetListUrl,
       "CONTENT-MAY-VARY": "YES",
       "TIMELINE-OCCUPIES": "POINT",
-      "TIMELINE-STYLE": getTimelineStyle(interstitials),
+      "TIMELINE-STYLE": getTimelineStyle(interstitial),
     };
 
     if (!isLive) {
@@ -36,79 +31,88 @@ export function getStaticDateRanges(session: Session, isLive: boolean) {
       clientAttributes["CUE"] = cue.join(",");
     }
 
-    dateRanges.push({
+    return {
       classId: "com.apple.hls.interstitial",
-      id: `${ts}`,
+      id: `${startDate.toMillis()}`,
       startDate,
       clientAttributes,
-    });
-  }
-
-  return dateRanges;
+    };
+  });
 }
 
 export async function getAssets(session: Session, dateTime: DateTime) {
   const assets: InterstitialAsset[] = [];
 
-  const interstitials = session.interstitials.filter((interstitial) =>
+  const interstitial = session.interstitials.find((interstitial) =>
     interstitial.dateTime.equals(dateTime),
   );
 
-  for (const interstitial of interstitials) {
-    if (interstitial.vast) {
-      const nextAssets = await getAssetsFromVast(interstitial.vast);
-      assets.push(...nextAssets);
-    }
+  if (interstitial?.vast) {
+    const nextAssets = await getAssetsFromVast(interstitial.vast);
+    assets.push(...nextAssets);
+  }
 
-    if (interstitial.asset) {
-      assets.push(interstitial.asset);
-    }
+  if (interstitial?.assets) {
+    assets.push(...interstitial.assets);
   }
 
   return assets;
 }
 
-function getGroupedInterstitials(interstitials: Interstitial[]) {
-  const result = new Map<number, Interstitial[]>();
-
+export function appendInterstitials(
+  source: Interstitial[],
+  interstitials: Interstitial[],
+) {
   for (const interstitial of interstitials) {
-    const ts = interstitial.dateTime.toMillis();
-    let items = result.get(ts);
-    if (!items) {
-      items = [];
-      result.set(ts, items);
+    const target = source.find((item) =>
+      item.dateTime.equals(interstitial.dateTime),
+    );
+
+    if (!target) {
+      source.push(interstitial);
+      continue;
     }
-    items.push(interstitial);
-  }
 
-  return result;
-}
+    if (interstitial.assets) {
+      if (!target.assets) {
+        target.assets = interstitial.assets;
+      } else {
+        target.assets.push(...interstitial.assets);
+      }
+    }
 
-function getAssetListUrl(
-  dateTime: DateTime,
-  interstitials: Interstitial[],
-  session?: Session,
-) {
-  if (interstitials.length === 1 && interstitials[0]?.assetList) {
-    return interstitials[0].assetList.url;
+    if (interstitial.vast) {
+      target.vast = interstitial.vast;
+    }
+
+    if (interstitial.assetList) {
+      target.assetList = interstitial.assetList;
+    }
   }
+}
 
+function getAssetListUrl(interstitial: Interstitial, session?: Session) {
+  if (interstitial.assetList) {
+    return interstitial.assetList.url;
+  }
   return createUrl("out/asset-list.json", {
-    dt: dateTime.toISO(),
+    dt: interstitial.dateTime.toISO(),
     sid: session?.id,
   });
 }
 
-function getTimelineStyle(interstitials: Interstitial[]) {
-  for (const interstitial of interstitials) {
-    if (
-      // If interstitial is an ad.
-      interstitial.asset?.kind === "ad" ||
-      // If interstitial is a VAST, thus it contains ads.
-      interstitial.vast
-    ) {
-      return "HIGHLIGHT";
+function getTimelineStyle(interstitial: Interstitial) {
+  if (interstitial.assets) {
+    for (const asset of interstitial.assets) {
+      if (asset.kind === "ad") {
+        return "HIGHLIGHT";
+      }
     }
   }
+
+  if (interstitial.vast) {
+    return "HIGHLIGHT";
+  }
+
   return "PRIMARY";
 }
diff --git a/packages/stitcher/src/playlist.ts b/packages/stitcher/src/playlist.ts
index bfbcd375..d3352568 100644
--- a/packages/stitcher/src/playlist.ts
+++ b/packages/stitcher/src/playlist.ts
@@ -1,6 +1,10 @@
 import { assert } from "shared/assert";
 import { filterMasterPlaylist, formatFilterToQueryParam } from "./filters";
-import { getAssets, getStaticDateRanges } from "./interstitials";
+import {
+  appendInterstitials,
+  getAssets,
+  getStaticDateRanges,
+} from "./interstitials";
 import { encrypt } from "./lib/crypto";
 import { createUrl, joinUrl, resolveUri } from "./lib/url";
 import {
@@ -15,6 +19,7 @@ import { fetchVmap, toAdBreakTimeOffset } from "./vmap";
 import type { Filter } from "./filters";
 import type { MasterPlaylist, MediaPlaylist, RenditionType } from "./parser";
 import type { Session } from "./session";
+import type { Interstitial } from "./types";
 import type { VmapAdBreak } from "./vmap";
 import type { DateTime } from "luxon";
 
@@ -190,8 +195,14 @@ async function initSessionOnMasterReq(session: Session) {
 
   if (session.vmap) {
     const vmap = await fetchVmap(session.vmap);
+
     delete session.vmap;
-    mapAdBreaksToSessionInterstitials(session, vmap.adBreaks);
+
+    const interstitials = mapAdBreaksToSessionInterstitials(
+      session,
+      vmap.adBreaks,
+    );
+    appendInterstitials(session.interstitials, interstitials);
 
     storeSession = true;
   }
@@ -205,6 +216,8 @@ export function mapAdBreaksToSessionInterstitials(
   session: Session,
   adBreaks: VmapAdBreak[],
 ) {
+  const interstitials: Interstitial[] = [];
+
   for (const adBreak of adBreaks) {
     const timeOffset = toAdBreakTimeOffset(adBreak);
 
@@ -214,7 +227,7 @@ export function mapAdBreaksToSessionInterstitials(
 
     const dateTime = session.startTime.plus({ seconds: timeOffset });
 
-    session.interstitials.push({
+    interstitials.push({
       dateTime,
       vast: {
         url: adBreak.vastUrl,
@@ -222,4 +235,6 @@ export function mapAdBreaksToSessionInterstitials(
       },
     });
   }
+
+  return interstitials;
 }
diff --git a/packages/stitcher/src/routes/session.ts b/packages/stitcher/src/routes/session.ts
index f085893d..f1934e5f 100644
--- a/packages/stitcher/src/routes/session.ts
+++ b/packages/stitcher/src/routes/session.ts
@@ -37,31 +37,29 @@ export const sessionRoutes = new Elysia()
         }),
         interstitials: t.Optional(
           t.Array(
-            t.Intersect([
-              t.Object({
-                time: t.Union([t.Number(), t.String()]),
-              }),
-              t.Union([
-                t.Object({
-                  type: t.Literal("asset"),
-                  uri: t.String(),
-                  kind: t.Optional(
-                    t.Union([t.Literal("ad"), t.Literal("bumper")]),
-                  ),
-                }),
+            t.Object({
+              time: t.Union([t.Number(), t.String()]),
+              assets: t.Optional(
+                t.Array(
+                  t.Object({
+                    uri: t.String(),
+                    kind: t.Optional(
+                      t.Union([t.Literal("ad"), t.Literal("bumper")]),
+                    ),
+                  }),
+                ),
+              ),
+              vast: t.Optional(
                 t.Object({
-                  type: t.Literal("vast"),
                   url: t.String(),
                 }),
+              ),
+              assetList: t.Optional(
                 t.Object({
-                  type: t.Literal("assetList"),
                   url: t.String(),
                 }),
-              ]),
-            ]),
-            {
-              description: "Manual HLS interstitial insertion.",
-            },
+              ),
+            }),
           ),
         ),
         filter: t.Optional(
diff --git a/packages/stitcher/src/session.ts b/packages/stitcher/src/session.ts
index bf6c6865..f236fcad 100644
--- a/packages/stitcher/src/session.ts
+++ b/packages/stitcher/src/session.ts
@@ -1,6 +1,7 @@
 import { randomUUID } from "crypto";
 import { DateTime } from "luxon";
 import { kv } from "./adapters/kv";
+import { appendInterstitials } from "./interstitials";
 import { JSON } from "./lib/json";
 import { resolveUri } from "./lib/url";
 import type { Interstitial } from "./types";
@@ -17,17 +18,19 @@ export interface Session {
   interstitials: Interstitial[];
 }
 
-type SessionInterstitial = {
+interface SessionInterstitial {
   time: number | string;
-} & (
-  | {
-      type: "asset";
-      uri: string;
-      kind?: "ad" | "bumper";
-    }
-  | { type: "vast"; url: string }
-  | { type: "assetList"; url: string }
-);
+  assets?: {
+    uri: string;
+    kind?: "ad" | "bumper";
+  }[];
+  vast?: {
+    url: string;
+  };
+  assetList?: {
+    url: string;
+  };
+}
 
 export async function createSession(params: {
   uri: string;
@@ -49,10 +52,11 @@ export async function createSession(params: {
   };
 
   if (params.interstitials) {
-    session.interstitials = mapSessionInterstitials(
+    const interstitials = mapSessionInterstitials(
       startTime,
       params.interstitials,
     );
+    appendInterstitials(session.interstitials, interstitials);
   }
 
   // We'll initially store the session for 10 minutes, if it's not been consumed
@@ -79,33 +83,21 @@ export async function updateSession(session: Session) {
 function mapSessionInterstitials(
   startTime: DateTime,
   interstitials: SessionInterstitial[],
-): Interstitial[] {
-  return interstitials.reduce<Interstitial[]>((acc, item) => {
+) {
+  return interstitials.map<Interstitial>((item) => {
+    const { time, assets, ...rest } = item;
     const dateTime =
-      typeof item.time === "string"
-        ? DateTime.fromISO(item.time)
-        : startTime.plus({ seconds: item.time });
-
-    if (item.type === "asset") {
-      acc.push({
-        dateTime,
-        asset: {
-          url: resolveUri(item.uri),
-          kind: item.kind,
-        },
-      });
-    } else if (item.type === "vast") {
-      acc.push({
-        dateTime,
-        vast: { url: item.url },
-      });
-    } else if (item.type === "assetList") {
-      acc.push({
-        dateTime,
-        assetList: { url: item.url },
-      });
-    }
+      typeof time === "string"
+        ? DateTime.fromISO(time)
+        : startTime.plus({ seconds: time });
 
-    return acc;
-  }, []);
+    return {
+      dateTime,
+      assets: assets?.map((asset) => {
+        const { uri, ...rest } = asset;
+        return { url: resolveUri(uri), ...rest };
+      }),
+      ...rest,
+    };
+  });
 }
diff --git a/packages/stitcher/src/types.ts b/packages/stitcher/src/types.ts
index 9aabab02..5326d966 100644
--- a/packages/stitcher/src/types.ts
+++ b/packages/stitcher/src/types.ts
@@ -11,11 +11,13 @@ export interface InterstitialAsset {
   kind?: "ad" | "bumper";
 }
 
+export interface InterstitialAssetList {
+  url: string;
+}
+
 export interface Interstitial {
   dateTime: DateTime;
-  asset?: InterstitialAsset;
+  assets?: InterstitialAsset[];
   vast?: InterstitialVast;
-  assetList?: {
-    url: string;
-  };
+  assetList?: InterstitialAssetList;
 }