How to create a stream based on a baseline in Architecture Management application

Hello,

I have created a global stream, assembling the initial local stream of the Architecture Management application (or Rational Model Manager, to be clear). Then I successfully create a global baseline, where a local baseline of AM is created implicitly.

Now I'm stuck when trying to create a global stream based on this global baseline because the GC application complains, that it can't create it.
Thus I tried it manually in the AM application, but couldn't find where.
 
Is this currently not supported for AM?
If not, is there a workaround to do this?

Kind regards