@Mac: Thanks a lot - as I wrote, I missed something obvious. Voicing a dom7 over the minor third of the root works perfectly, at least as long as the style or realtrack does support slash chords, which is not always the case. And sure you want to hear a b9 in the chord when practicing Dorian b9 mode. ;-)

Anyway, I think BIAB should provide the chords of the main scales that is Major, HM and MM imho. Maybe that's something for the wishlist.