For midi, on the melody or soloist track you could input diminishing control 7 (Volume) changes for all of your instruments over the repeating chords at the end of the tune. First determine what channels bass, piano, melody, etc are set to and then inset Control 7s for each of those channels. You could also use Control 11(Expression), but I would encourage the use of Volume instead because Biab resets volumes at the start of the song.

JBlatz