I'm not really sure what to say aside from being really surprised your demasoni haven't killed each other yet. They're really aggressive to one another, typically best kept in groups of 12+.
What kind of peacocks do you have? I think they need bigger tanks in an average situation. I honestly don't know much about them though, they've never interested me.
Also, two rocks isn't really a lot. I've got about 30 of them, and that's for a tank which is going to have 6 julidochromis as rock dwellers, nevermind aggressive mbuna.