I have a model and have imported an acapella song for him to sing. The timeline "Lips" movement is perfect. I have also imported a "background audio track"  from a different band that I want to use as the primary source.
My question is...on the "acapella" track, how do I lower/eliminate the vocals but keep the lip-movement so the model appears to be singing to the background track.
I currently have it all synched-up but the acapella voice can still be heard.
Thanks for any suggestions you have!

And it's the last version for multiple characters.