Keep converted midi instruments to audio in BIAB. Display them where they can be combined with the arrangement. This would would free up the midi track another instrument. It would also allow for plug in effects to the audio version such as tone, reverb. You could add them to the right of the main screen in the black area. This would also allow for adding more instruments to an arrangement.

This sure would be helpful. One would not have to move them to Sonar for audio effects with plug ins.