Rather than "facts on chromis" how 'bout "opinions on chromis"?
IMO - if you get a large group of chromis, and have a large aquarium, and if there are other large fish (not predators of course) in with them, the chromis will "seek safety in numbers" and get along pretty well. Kinda like they pick the lesser of two evils. Put four in a 75 gallon tank with few other fish, and they will often bicker and work on each other until there is one.
D'oh!, after I wrote that, it looks like you may be talking about mixing different SPECIES of chromis - sorry, nevermind, I don't have an opinion on that.....
Jay