I contacted PG and this was their reply.
That doesn't appear to be possible, but you can do something similar using subgroups on the mixer.
Real Band is a very, very basic DAW. PG has a lot of work to do to it if they are interested in competing in the DAW marketplace.
This and other things are the reason I use Sonar as my DAW and use RB to generate my tracks in audio form.
PG has an awesome piece of software with BB & RB because they do what no other DAW in the world can do, and that is to create the music in a very realistic manner. I don't know that they would gain much by trying to compete in the DAW world since the other DAW companies really have all the bases covered quite well. I think PG should focus on what they do best and work on making it better and larger. Why be the small fish in the big ocean when you're already the only fish in the other ocean?