Differentiate vocals with EQ pokes
If you put a little mid EQ boost on your vocals to get them to pop (which you should definitely do! Try Q=1.8), and if you vary the boost frequency for different vocals, you can get them to differentiate from each other so easily!
Try this: put the boost frequency at like 1,200 Hz for the backing vocal bus, and at like 1,600 Hz for the lead vocal. Or vice versa, depending on the voices involved.
Hear how the lead vocal pops out, and the backing vocals sound very well-defined but also out of the way of the lead vocal? It’s because you’ve given them each their own space.
Gotta keep ‘em separated — jamie