I'm still trying to get a hang of this feature but I like what I think it does. One of the things I regularly download is audiobooks from Usenet. There are a half dozen newsgroups and combining them means that I can search one list of all the available books. Good thing!
When I create the combined newsgroup I'm asked for a name but it doesn't appear that this name is persisted. What I would really like is to save this combined newsgroup so it is available every time I start the software. A command to download headers from this virtual newsgroup would propagate this command to all newsgroup children. Ultimately it should support all commands that a normal newsgroup supports.