foreign primary key to foreign primary key

In the below example (disregard User, its just a simple auto incremnt entity) i want to express GroupTopicMember's pk is a foreign key to GroupTopic that in turn has pk that is a foreign key to ChatTopic. It needs to be that chain cause there can be no GroupTopicMember if theres no GroupTopic. When compiling this program i get

• Not in scope: type constructor or class ‘ChatTopicId’

ChatTopic
  ct_name String sql=name
  deriving Show Eq Generic

GroupTopic
  pcm_topicId ChatTopicId sql=topic_id
  Primary pcm_topicId
  deriving Show Eq Generic

GroupTopicMember
  prtm_userId UserId sql=user_id
  prtm_topicId GroupTopicId sql=topic_id
  Primary prtm_userId prtm_topicId
  deriving Show Eq Generic

...as if its not yet aware of ChatTopicId when it tried to construct the GroupTopicMemberKey? If i change prtm_topicId to ChatTopicId it compiles but the resulting migration created foreign key goes from GroupTopicMember to ChatTopic - which is not correct association. Im using mysql, if that explains anything. (Note, there are more "xyz-chat-topic" entities not shown here - but these have direct association to ChatTopic and doesnt have associated entities, so works wo problem. ChatTopic is conceptually a sumtype, but dont know if I could model such using Persistent)

The supplied ChatTopic, GroupTopic, and GroupTopicMember definitions are the reproduction; start by compiling them with the MySQL backend and inspecting the generated migration. Done means the chained primary-key model compiles and the resulting foreign key points from GroupTopicMember to GroupTopic.