Hey man,
I hear what you're talking about for sure, although I think you'd get away with it if the mix was more in favour of the main vocal as one thing, and the rest as another.
Right now the guy you described (right hand side) is actually drawing my attention more than the main vocal is, and I don't think it's just because he is being discussed.
The tone of his voice cuts through a little more, whereas main vocal is quite soft and rounded.
I think I'd want to mute the main vocal and try to mix the rest in such a way that no one person sticks out.
I'd be using an eq or pretty hard compression on Frank to take the edge off him, and maybe narrow the bvox as a group.
Bringing the main voice back in, I'd centre it. It's slightly off to the left, yeah?
Just my thoughts. It was a nice listen, all that aside.