I just finished a Sonny and Cher Duet. I put all the vocals on the vocal track, put Sonny's part on Harm1, and Cher's on Harm2. I made a DryVox from the Harm1 part (and put it into Magma), and another from the Harm2 notes.
I want the camera to cut back and forth between the two singers, so I did the venue camera cuts by hand - mostly alternating between the main singer and the bass player (with a bassist sing along marker for each Cher section).
The camera is doing just what I want, with cuts to the bass/Cher at just the right moments. The lead singer has good animated vocals, but the bassist's lips never move.
Any idea where I messed up?