I hardly work with this feature (yet) but I checked and saw this:

Under the "melodist"button, after the "generate chords and/or melody"screen pops up, there is at the right hand side the option for "part of the song"or "whole song"
I assume if you select the range there by typing the bar and chorus it has to start and the duration in bars, it should work. I hope that answers your question?

I'll be back...