diff --git a/packages/api/src/archive/service/backfill_ledger.ts b/packages/api/src/archive/service/backfill_ledger.ts
index 929c1883..c787234a 100644
--- a/packages/api/src/archive/service/backfill_ledger.ts
+++ b/packages/api/src/archive/service/backfill_ledger.ts
@@ -35,6 +35,7 @@ export const backfillLedger = async (archiveId: string): Promise<void> => {
 					id: record.recordId,
 					body: JSON.stringify(message),
 					attributes: { Entity: "record", Action: "create" },
+					messageGroupId: "admin",
 				})
 				.catch((err: unknown) => {
 					logger.error(err);
diff --git a/packages/event_send/src/service.ts b/packages/event_send/src/service.ts
index c1fe79ac..16cc4c2f 100644
--- a/packages/event_send/src/service.ts
+++ b/packages/event_send/src/service.ts
@@ -78,6 +78,7 @@ export const sendEvents = async (): Promise<void> => {
 			body: event.body,
 		}),
 		attributes: { Entity: event.entity, Action: event.action },
+		messageGroupId: event.actorId,
 	}));
 
 	for (const event of events.rows) {
diff --git a/packages/publisher-utils/src/index.test.ts b/packages/publisher-utils/src/index.test.ts
index 5d94de0f..b3ccbd61 100644
--- a/packages/publisher-utils/src/index.test.ts
+++ b/packages/publisher-utils/src/index.test.ts
@@ -185,6 +185,38 @@ describe("batchPublishMessages", () => {
 			process.env["AWS_ENDPOINT_URL"] = originalEndpoint;
 		}
 	});
+
+	test("should set MessageGroupId only on messages that provide one", async () => {
+		mockSend.mockResolvedValue({ Failed: [] });
+
+		const messages = [
+			{ id: "1", body: "message 1", messageGroupId: "tenant-a" },
+			{ id: "2", body: "message 2" },
+		];
+
+		await publisherClient.batchPublishMessages("topic", messages);
+
+		const {
+			mock: {
+				calls: [firstCallArguments],
+			},
+		} = mockSend as {
+			mock: { calls: Array<Array<{ __input: PublishBatchInput }>> };
+		};
+		expect(firstCallArguments).toBeDefined();
+		if (firstCallArguments !== undefined) {
+			expect(firstCallArguments[0]).toBeDefined();
+			if (firstCallArguments[0] !== undefined) {
+				expect(firstCallArguments[0].__input).toEqual({
+					TopicArn: "topic",
+					PublishBatchRequestEntries: [
+						{ Id: "1", Message: "message 1", MessageGroupId: "tenant-a" },
+						{ Id: "2", Message: "message 2" },
+					],
+				});
+			}
+		}
+	});
 });
 
 describe("publishMessage", () => {
diff --git a/packages/publisher-utils/src/index.ts b/packages/publisher-utils/src/index.ts
index 2e3a427d..17bfc837 100644
--- a/packages/publisher-utils/src/index.ts
+++ b/packages/publisher-utils/src/index.ts
@@ -11,6 +11,7 @@ export interface Message {
 	id: string;
 	body: string;
 	attributes?: Record<string, string>;
+	messageGroupId?: string;
 }
 
 const CHUNK_SIZE = 10;
@@ -50,6 +51,9 @@ const batchPublishMessages = async (
 							]),
 						);
 					}
+					if (message.messageGroupId !== undefined) {
+						entry.MessageGroupId = message.messageGroupId;
+					}
 					return entry;
 				}),
 			});