diff --git a/nimble/host/audio/services/bass/include/services/bass/ble_audio_svc_bass.h b/nimble/host/audio/services/bass/include/services/bass/ble_audio_svc_bass.h
index 48f1a53232..873ac7ae62 100644
--- a/nimble/host/audio/services/bass/include/services/bass/ble_audio_svc_bass.h
+++ b/nimble/host/audio/services/bass/include/services/bass/ble_audio_svc_bass.h
@@ -327,8 +327,6 @@ struct ble_svc_audio_bass_operation {
             /** Number of subgroups */
             uint16_t num_subgroups;
 
-            /** BIS Synchronisation of subgroups */
-            uint32_t bis_sync[BLE_SVC_AUDIO_BASS_SUB_NUM_MAX];
             /** Subgroup entries */
             struct ble_svc_audio_bass_subgroup
                 subgroups[BLE_SVC_AUDIO_BASS_SUB_NUM_MAX];
diff --git a/nimble/host/audio/services/bass/src/ble_audio_svc_bass.c b/nimble/host/audio/services/bass/src/ble_audio_svc_bass.c
index cc4805f951..501898b4a7 100644
--- a/nimble/host/audio/services/bass/src/ble_audio_svc_bass.c
+++ b/nimble/host/audio/services/bass/src/ble_audio_svc_bass.c
@@ -466,6 +466,27 @@ ble_svc_audio_bass_add_source(uint8_t *data, uint16_t data_len, uint16_t conn_ha
 }
 
 static int
+check_bis_sync(uint16_t num_subgroups, struct ble_svc_audio_bass_subgroup *subgroups)
+{
+    uint32_t bis_sync_mask = 0;
+    int i;
+    int j;
+
+    for (i = 0; i < num_subgroups; i++) {
+        if (subgroups[i].bis_sync != 0xFFFFFFFF) {
+            for (j = 0; j < num_subgroups; j++) {
+                if (subgroups[i].bis_sync & bis_sync_mask) {
+                    return BLE_HS_EINVAL;
+                }
+
+                bis_sync_mask |= subgroups[i].bis_sync;
+            }
+        }
+    }
+
+    return 0;
+}
+
 ble_svc_audio_bass_modify_source(uint8_t *data, uint16_t data_len, uint16_t conn_handle)
 {
     struct ble_svc_audio_bass_operation operation;
@@ -517,7 +538,7 @@ ble_svc_audio_bass_modify_source(uint8_t *data, uint16_t data_len, uint16_t conn
     }
 
     for (i = 0; i < operation.modify_source.num_subgroups; i++) {
-        operation.modify_source.bis_sync[i] = get_le32(&data[offset]);
+        operation.modify_source.subgroups.bis_sync[i] = get_le32(&data[offset]);
         offset += 4;
         operation.modify_source.subgroups[i].metadata_length = data[offset++];
         data_len -= 5;
@@ -532,7 +553,7 @@ ble_svc_audio_bass_modify_source(uint8_t *data, uint16_t data_len, uint16_t conn
     }
 
     if (check_bis_sync(operation.modify_source.num_subgroups,
-                       operation.modify_source.bis_sync)) {
+                       operation.modify_source.subgroups)) {
         rc = BLE_HS_EINVAL;
         ev.bass_operation_status.status = BLE_HS_EREJECT;
         goto done;
diff --git a/nimble/host/audio/src/ble_audio_scan_delegator.c b/nimble/host/audio/src/ble_audio_scan_delegator.c
index 60e04adc36..08a5ac645d 100644
--- a/nimble/host/audio/src/ble_audio_scan_delegator.c
+++ b/nimble/host/audio/src/ble_audio_scan_delegator.c
@@ -197,8 +197,9 @@ bass_modify_source_op_handler(struct ble_svc_audio_bass_operation *op, void *arg
     BLE_AUDIO_DBG_ASSERT(sync_opt->num_subgroups < ARRAY_SIZE(sync_opt->subgroups));
 
     for (uint8_t i = 0; i < sync_opt->num_subgroups; i++) {
-        sync_opt->subgroups[i].bis_sync = op->modify_source.bis_sync[i];
-        /* FIXME: Missing metadata in Modify Source */
+        sync_opt->subgroups[i].bis_sync = op->modify_source.subgroups[i].bis_sync_state;
+        sync_opt->subgroups[i].metadata_length = op->modify_source.subgroups[i].metadata_length;
+        sync_opt->subgroups[i].metadata = op->modify_source.subgroups[i].metadata;
     }
 
     action.type = BLE_AUDIO_SCAN_DELEGATOR_ACTION_SOURCE_MODIFY;