Look at multistyles. They have ABCD... sections. Each pair (a/b, c/d) can have it's own instrument definitions. BIAB provides some Multistyles and can be found in the StylePicker. One of those may do what you want. If not, the Stylemaker can be used to create and customize your own Multistyles.

Get back to us if you want to dive more into the Stylemaker. I have a number of 'custom' styles that do exactly what you are asking. It is an easy thing to do.

R