referenced processes return document goes into DLQ

I am using BPM with referenced processes in webMethods version 8.
I order to make referenced processes work, the child process needs to have a publish step at the end. This basically publishes a Broker document. After this has been done the higher level process resumes. I am not sure if you have noticed this, but there is no subscription/receive step in the higher level process for this return document. This gets confirmed when looking at the Integration Server level, there is no subscription for the document that has been published by the child process. I do not really care how the data goes back to the higher level process, but due to the fact that there is no subscription, the published document ends up in the Dead Letter Queue and fills up the Broker storage.

Does anybody know if this is expected or have you ever seen this? Also, anybody knows a way around this?