Polar:

There's a way to do that right in BIAB.
I assume you're using version 2014 (others may be similar).
Use File > Open MIDI file ... then select it, then Open ...to get it into BIAB.
Then click on the green SEQ Sequencer button and select Sequencer on Melody Track.
From there you can Play, Show or mute any of the MIDI channels.

Good luck!
LLOYD S