I don't know if this will help I posted somewhere else ?
"The workaround i do is where you have a hold, shot or stop on say a C chord C... C.. C. and you want the guitar to keep playing, just add a "g" on the end C...g and in the BB guitar track, generate the track, duplicate it then regenerate another instrument in the same BB guitar track, duplicate it and so on and so forth.
That way you are not limited with just the BB tracks for exemptions:
C...b bass is exempt
C...d drums " "
C...p piano " "
C...g guitar " "
C...s strings " "

You just won't get the realcharts as the BB tracks don't generate realcharts.

Bob.. "