Jan,
I use the VoiceWorks to sing my own versions and arrangements in a “The Four Freshmen”-style all by myself.

I use the "output chords option" in Band in a Box and use the chords I have entered in my song. As this function only works with 3 and 4 note chords, there are some restrictions; C7#5 is OK, but C7#9 is not OK. I often bypass this by writing my arrangements with full chords, then freeze e.g. piano track. Then I reduce all chords to 4 note chords, so e.g. C9 becomes C7 etc. This way VoiceWorks will work OK, while BiaB is still sounding the full chords.

Also I enter passing chords if the melody only move one half step or one whole step, as the other voices then remain stationary, while I want them to move. So when the melody moves e, f, g and the chords is Cmaj7, I would enter e.g. Cmaj7, Dm7, Em7.

Hope this helps.

Tonnie