I've been sort of successful in entering flatted chords using BIAB chord entry, but only if I am using Roman Numeral notation. But I'm not sure if there is an official way of entering such chords. There is also chords that are borrowed from the major or minor scale of the scaled being used in the song. It's not too much of a a problem to determine the actual chord and then entering it in the normal way. But if there was a way to incorporate this in the notation of BiaB then it would be a more friendly way to work.

If anybody could shed some light that would be great.

Thanks