I don't have the 2014 version (yet), so I'm haven't been able to verify how BiaB behaves. But Chris_Kn noted that if a particular type of chord wasn't found in a User Style, BiaB would simply not generate anything.

Would it be possible for BiaB to have a fallback list as an option? Some possible substitutions:

C5 -> C
C7 -> C
Cm7 -> Cm, E/C
Csus4 -> F/C
Cmaj7 -> Em/C, C
Cmaj9 -> Em7/C, G/C
C11 -> Gm7/C, Gm/C, Bb/C
Cdim -> Ebm

If the set is really sparse, a fallback might have to call another fallback, so:

Cmaj7 -> Em/C -> G/C -> G

This obviously isn't optimal, but it's probably more helpful than not outputting anything at all.

I know that I could generate these substitutions by hand, but that would cause problems for tracks that do have the right chords.

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?