Hello dhs,
You don’t mention your Melodyne edition, but I suppose you are using the DNA algorithm in Melodyne editor, right? Originally, DNA was designed for single polyphonic instruments. But I guess you can’t stop people from feeding it with full mixes and ensemble tracks, can you?

Anyway, there is currently no grouping option, and I can see where your suggestion might make sense. I will gladly move your thread to our Features Wish List.