If you create a MIDI track in Band-in-a-Box then manually adjust the velocity for each of the notes, those adjustments will be saved to that track and should remain with the track if saved and exported. As far as extending the dynamic range of the velocity adjustments upon exporting, I don't know of any program that has that feature.

RealTracks are full recordings, lasting from 1 to 8 bars at a time that Band-in-a-Box rearranges to play to along to your entered chord progression.

We hope this helps!

Best,

Jerry