^^ what Bob Calver said
Use multiple tracks, enter the notes any way you want (piano roll, MIDI, physical entry etc)
And if you set the tempo correctly you can still use BiaB generate features, though it sounds like you may not be, which again leads to the 'why use BiaB for this' question.

Anyway, Realband will likely make your described workflow better

I do not work here, but the benefits are still awesome
Make your sound your own!