diff --git a/ydb/core/tx/replication/service/json_change_record.cpp b/ydb/core/tx/replication/service/json_change_record.cpp
index d6d5808775e8..b11565aed63c 100644
--- a/ydb/core/tx/replication/service/json_change_record.cpp
+++ b/ydb/core/tx/replication/service/json_change_record.cpp
@@ -33,6 +33,10 @@ NChangeExchange::IChangeRecord::EKind TChangeRecord::GetKind() const {
         : EKind::CdcDataChange;
 }
 
+TString TChangeRecord::GetSourceId() const {
+    return SourceId;
+}
+
 static bool ParseKey(TVector<TCell>& cells,
         const NJson::TJsonValue::TArray& key, TLightweightSchema::TCPtr schema, TMemoryPool& pool, TString& error)
 {
diff --git a/ydb/core/tx/replication/service/json_change_record.h b/ydb/core/tx/replication/service/json_change_record.h
index e8c7f5f9c32a..89f5076fa6ca 100644
--- a/ydb/core/tx/replication/service/json_change_record.h
+++ b/ydb/core/tx/replication/service/json_change_record.h
@@ -40,6 +40,7 @@ class TChangeRecord: public NChangeExchange::TChangeRecordBase {
     ui64 GetStep() const override;
     ui64 GetTxId() const override;
     EKind GetKind() const override;
+    TString GetSourceId() const;
 
     void Serialize(NKikimrTxDataShard::TEvApplyReplicationChanges::TChange& record, TMemoryPool& pool) const;
     void Serialize(NKikimrTxDataShard::TEvApplyReplicationChanges::TChange& record) const;
@@ -48,6 +49,7 @@ class TChangeRecord: public NChangeExchange::TChangeRecordBase {
     TConstArrayRef<TCell> GetKey() const;
 
 private:
+    TString SourceId;
     NJson::TJsonValue JsonBody;
     TLightweightSchema::TCPtr Schema;
 
@@ -59,6 +61,11 @@ class TChangeRecordBuilder: public NChangeExchange::TChangeRecordBuilder<TChange
 public:
     using TBase::TBase;
 
+    TSelf& WithSourceId(const TString& sourceId) {
+        GetRecord()->SourceId = sourceId;
+        return static_cast<TSelf&>(*this);
+    }
+
     template <typename T>
     TSelf& WithBody(T&& body) {
         auto res = NJson::ReadJsonTree(body, &GetRecord()->JsonBody);
diff --git a/ydb/core/tx/replication/service/table_writer.cpp b/ydb/core/tx/replication/service/table_writer.cpp
index 92ff2650cda7..bf9858bda3c3 100644
--- a/ydb/core/tx/replication/service/table_writer.cpp
+++ b/ydb/core/tx/replication/service/table_writer.cpp
@@ -76,11 +76,21 @@ class TTablePartitionWriter: public TActorBootstrapped<TTablePartitionWriter> {
         tableId.SetTableId(TableId.PathId.LocalPathId);
         tableId.SetSchemaVersion(TableId.SchemaVersion);
 
+        TString source;
         for (auto recordPtr : ev->Get()->Records) {
             MemoryPool.Clear();
             const auto& record = *recordPtr->Get<TChangeRecord>();
             record.Serialize(*event->Record.AddChanges(), MemoryPool);
-            // TODO: set WriteTxId, Source
+
+            if (!source) {
+                source = record.GetSourceId();
+            } else {
+                Y_ABORT_UNLESS(source == record.GetSourceId());
+            }
+        }
+
+        if (source) {
+            event->Record.SetSource(source);
         }
 
         Send(LeaderPipeCache, new TEvPipeCache::TEvForward(event.Release(), TabletId, false));
@@ -427,6 +437,7 @@ class TLocalTableWriter
         for (auto& record : ev->Get()->Records) {
             records.emplace_back(record.Offset, PathId, record.Data.size());
             auto res = PendingRecords.emplace(record.Offset, TChangeRecordBuilder()
+                .WithSourceId(ev->Get()->Source)
                 .WithOrder(record.Offset)
                 .WithBody(std::move(record.Data))
                 .WithSchema(Schema)
diff --git a/ydb/core/tx/replication/service/table_writer_ut.cpp b/ydb/core/tx/replication/service/table_writer_ut.cpp
index ade2ae2bda81..2de0a0a7710a 100644
--- a/ydb/core/tx/replication/service/table_writer_ut.cpp
+++ b/ydb/core/tx/replication/service/table_writer_ut.cpp
@@ -31,7 +31,7 @@ Y_UNIT_TEST_SUITE(LocalTableWriter) {
         env.Send<TEvWorker::TEvHandshake>(writer, new TEvWorker::TEvHandshake());
 
         using TRecord = TEvWorker::TEvData::TRecord;
-        env.Send<TEvWorker::TEvPoll>(writer, new TEvWorker::TEvData({
+        env.Send<TEvWorker::TEvPoll>(writer, new TEvWorker::TEvData("TestSource", {
             TRecord(1, R"({"key":[1], "update":{"value":"10"}})"),
             TRecord(2, R"({"key":[2], "update":{"value":"20"}})"),
             TRecord(3, R"({"key":[3], "update":{"value":"30"}})"),
@@ -72,7 +72,7 @@ Y_UNIT_TEST_SUITE(LocalTableWriter) {
         env.Send<TEvWorker::TEvHandshake>(writer, new TEvWorker::TEvHandshake());
 
         using TRecord = TEvWorker::TEvData::TRecord;
-        env.Send<TEvWorker::TEvPoll>(writer, new TEvWorker::TEvData({
+        env.Send<TEvWorker::TEvPoll>(writer, new TEvWorker::TEvData("TestSource", {
             TRecord(1, R"({"key":[1], "update":{"int32_value":-100500}})"),
             TRecord(2, R"({"key":[2], "update":{"uint32_value":100500}})"),
             TRecord(3, R"({"key":[3], "update":{"int64_value":-200500}})"),
diff --git a/ydb/core/tx/replication/service/topic_reader.cpp b/ydb/core/tx/replication/service/topic_reader.cpp
index d4d9ba4acf9c..8e3133a122c9 100644
--- a/ydb/core/tx/replication/service/topic_reader.cpp
+++ b/ydb/core/tx/replication/service/topic_reader.cpp
@@ -61,7 +61,7 @@ class TRemoteTopicReader: public TActor<TRemoteTopicReader> {
             records.emplace_back(msg.GetOffset(), std::move(msg.GetData()));
         }
 
-        Send(Worker, new TEvWorker::TEvData(std::move(records)));
+        Send(Worker, new TEvWorker::TEvData(ToString(result.PartitionId), std::move(records)));
     }
 
     void Handle(TEvYdbProxy::TEvTopicReaderGone::TPtr& ev) {
diff --git a/ydb/core/tx/replication/service/worker.cpp b/ydb/core/tx/replication/service/worker.cpp
index 8f2be72c6aa5..bef2b853480f 100644
--- a/ydb/core/tx/replication/service/worker.cpp
+++ b/ydb/core/tx/replication/service/worker.cpp
@@ -23,13 +23,15 @@ TEvWorker::TEvData::TRecord::TRecord(ui64 offset, TString&& data)
 {
 }
 
-TEvWorker::TEvData::TEvData(const TVector<TRecord>& records)
-    : Records(records)
+TEvWorker::TEvData::TEvData(const TString& source, const TVector<TRecord>& records)
+    : Source(source)
+    , Records(records)
 {
 }
 
-TEvWorker::TEvData::TEvData(TVector<TRecord>&& records)
-    : Records(std::move(records))
+TEvWorker::TEvData::TEvData(const TString& source, TVector<TRecord>&& records)
+    : Source(source)
+    , Records(std::move(records))
 {
 }
 
@@ -42,6 +44,7 @@ void TEvWorker::TEvData::TRecord::Out(IOutputStream& out) const {
 
 TString TEvWorker::TEvData::ToString() const {
     return TStringBuilder() << ToStringHeader() << " {"
+        << " Source: " << Source
         << " Records [" << JoinSeq(",", Records) << "]"
     << " }";
 }
@@ -115,7 +118,7 @@ class TWorker: public TActorBootstrapped<TWorker> {
                 << ": sender# " << ev->Sender);
 
             Reader.Registered();
-            if (!InFlightRecords) {
+            if (!InFlightData) {
                 Send(Reader, new TEvWorker::TEvPoll());
             }
         } else if (ev->Sender == Writer) {
@@ -123,8 +126,8 @@ class TWorker: public TActorBootstrapped<TWorker> {
                 << ": sender# " << ev->Sender);
 
             Writer.Registered();
-            if (InFlightRecords) {
-                Send(Writer, new TEvWorker::TEvData(InFlightRecords));
+            if (InFlightData) {
+                Send(Writer, new TEvWorker::TEvData(InFlightData->Source, InFlightData->Records));
             }
         } else {
             LOG_W("Handshake from unknown actor"
@@ -142,7 +145,7 @@ class TWorker: public TActorBootstrapped<TWorker> {
             return;
         }
 
-        InFlightRecords.clear();
+        InFlightData.Reset();
         if (Reader) {
             Send(ev->Forward(Reader));
         }
@@ -157,8 +160,8 @@ class TWorker: public TActorBootstrapped<TWorker> {
             return;
         }
 
-        Y_ABORT_UNLESS(InFlightRecords.empty());
-        InFlightRecords = ev->Get()->Records;
+        Y_ABORT_UNLESS(!InFlightData);
+        InFlightData = MakeHolder<TEvWorker::TEvData>(ev->Get()->Source, ev->Get()->Records);
 
         if (Writer) {
             Send(ev->Forward(Writer));
@@ -239,7 +242,7 @@ class TWorker: public TActorBootstrapped<TWorker> {
     mutable TMaybe<TString> LogPrefix;
     TActorInfo Reader;
     TActorInfo Writer;
-    TVector<TEvWorker::TEvData::TRecord> InFlightRecords;
+    THolder<TEvWorker::TEvData> InFlightData;
 };
 
 IActor* CreateWorker(std::function<IActor*(void)>&& createReaderFn, std::function<IActor*(void)>&& createWriterFn) {
diff --git a/ydb/core/tx/replication/service/worker.h b/ydb/core/tx/replication/service/worker.h
index 523214190ac1..b5d43de7a7a6 100644
--- a/ydb/core/tx/replication/service/worker.h
+++ b/ydb/core/tx/replication/service/worker.h
@@ -36,10 +36,11 @@ struct TEvWorker {
             void Out(IOutputStream& out) const;
         };
 
+        TString Source;
         TVector<TRecord> Records;
 
-        explicit TEvData(const TVector<TRecord>& records);
-        explicit TEvData(TVector<TRecord>&& records);
+        explicit TEvData(const TString& source, const TVector<TRecord>& records);
+        explicit TEvData(const TString& source, TVector<TRecord>&& records);
         TString ToString() const override;
     };
 
diff --git a/ydb/core/tx/replication/ydb_proxy/ydb_proxy.cpp b/ydb/core/tx/replication/ydb_proxy/ydb_proxy.cpp
index 942fa445e524..fc87485174c5 100644
--- a/ydb/core/tx/replication/ydb_proxy/ydb_proxy.cpp
+++ b/ydb/core/tx/replication/ydb_proxy/ydb_proxy.cpp
@@ -33,6 +33,7 @@ void TEvYdbProxy::TReadTopicResult::TMessage::Out(IOutputStream& out) const {
 
 void TEvYdbProxy::TReadTopicResult::Out(IOutputStream& out) const {
     out << "{"
+        << " PartitionId: " << PartitionId
         << " Messages [" << JoinSeq(",", Messages) << "]"
     << " }";
 }
diff --git a/ydb/core/tx/replication/ydb_proxy/ydb_proxy.h b/ydb/core/tx/replication/ydb_proxy/ydb_proxy.h
index 04114b5337ae..059449e4180d 100644
--- a/ydb/core/tx/replication/ydb_proxy/ydb_proxy.h
+++ b/ydb/core/tx/replication/ydb_proxy/ydb_proxy.h
@@ -186,6 +186,7 @@ struct TEvYdbProxy {
         };
 
         explicit TReadTopicResult(const NYdb::NTopic::TReadSessionEvent::TDataReceivedEvent& event) {
+            PartitionId = event.GetPartitionSession()->GetPartitionId();
             Messages.reserve(event.GetMessagesCount());
             if (event.HasCompressedMessages()) {
                 for (const auto& msg : event.GetCompressedMessages()) {
@@ -200,6 +201,7 @@ struct TEvYdbProxy {
 
         void Out(IOutputStream& out) const;
 
+        ui64 PartitionId;
         TVector<TMessage> Messages;
     };