diff --git a/LEGO1/mxstreamcontroller.cpp b/LEGO1/mxstreamcontroller.cpp
index 74df9dc9..e45435ac 100644
--- a/LEGO1/mxstreamcontroller.cpp
+++ b/LEGO1/mxstreamcontroller.cpp
@@ -290,9 +290,22 @@ MxNextActionDataStart* MxStreamController::FindNextActionDataStartFromStreamingA
 	return m_nextActionList.Find(p_action->GetObjectId(), p_action->GetUnknown24());
 }
 
-// STUB: LEGO1 0x100c20d0
+// FUNCTION: LEGO1 0x100c20d0
 MxBool MxStreamController::FUN_100c20d0(MxDSObject& p_obj)
 {
-	// TODO
+	if (m_subscriberList.Find(&p_obj))
+		return FALSE;
+
+	if (p_obj.IsA("MxDSMultiAction")) {
+		MxDSActionList* actions = ((MxDSMultiAction&) p_obj).GetActionList();
+		MxDSActionListCursor cursor(actions);
+		MxDSAction* action;
+
+		while (cursor.Next(action)) {
+			if (!FUN_100c20d0(*action))
+				return FALSE;
+		}
+	}
+
 	return TRUE;
 }
diff --git a/LEGO1/mxstreamlist.cpp b/LEGO1/mxstreamlist.cpp
index d422c1cb..729b0d7b 100644
--- a/LEGO1/mxstreamlist.cpp
+++ b/LEGO1/mxstreamlist.cpp
@@ -5,6 +5,20 @@ DECOMP_SIZE_ASSERT(MxStreamListMxDSAction, 0xc);
 DECOMP_SIZE_ASSERT(MxStreamListMxNextActionDataStart, 0xc);
 DECOMP_SIZE_ASSERT(MxStreamListMxDSSubscriber, 0xc);
 
+// FUNCTION: LEGO1 0x100b8450
+MxDSSubscriber* MxStreamListMxDSSubscriber::Find(MxDSObject* p_object)
+{
+	for (iterator it = begin(); it != end(); it++) {
+		if (p_object->GetObjectId() == -1 || p_object->GetObjectId() == (*it)->GetObjectId()) {
+			if (p_object->GetUnknown24() == -2 || p_object->GetUnknown24() == (*it)->GetUnknown48()) {
+				return *it;
+			}
+		}
+	}
+
+	return NULL;
+}
+
 // FUNCTION: LEGO1 0x100bfa80
 MxDSAction* MxStreamListMxDSAction::Find(MxDSAction* p_action, MxBool p_delete)
 {
diff --git a/LEGO1/mxstreamlist.h b/LEGO1/mxstreamlist.h
index 86b9a002..f9164bfb 100644
--- a/LEGO1/mxstreamlist.h
+++ b/LEGO1/mxstreamlist.h
@@ -46,6 +46,9 @@ public:
 };
 
 // SIZE 0xc
-class MxStreamListMxDSSubscriber : public MxStreamList<MxDSSubscriber*> {};
+class MxStreamListMxDSSubscriber : public MxStreamList<MxDSSubscriber*> {
+public:
+	MxDSSubscriber* Find(MxDSObject* p_object);
+};
 
 #endif // MXSTREAMLIST_H