Hi,
This is not a solution for BIAB, but I would suggest saving your file as a midi file. Then importing it into the sequencer of your choice. I rough out tunes in BIAB and import the midi files into Garage Band or Logic. There you can do whatever you want. The only hangup I have found is that the bass midi file is 1 octave too low. So I have to transpose it an octave up. Apart from that, it's great.

TakeCare
Bill