Sometimes with an imported MIDI multichannel track i look at the individual channels & notes being there in the piano-roll editor. Then i make a copy of that onto the soloist track, to switch back if needed (by copying).

Then i erase the MIDI and re-import the original MIDI track selecting only the channel i need. For drums that's usually channel 10.

Maybe there's a quicker way, but i would like to see a BIAB with more flexible tracks than just the two, and advanced editing possibilities (like splitting a mutlti midi automatically onto different tracks all at once). Of course one can use RealBand, but getting back your edits into BIAB might not be so easy. -F