Hey, there!

Part of my livestock includes three blue-green chromis (Chromis viridis) in a 140-gal, and I'm interested in enlarging the shoal to six or seven. I'm not worried about biological capacity - the tank's not heavily stocked, and I've got a good skimmer. Can I simply add more chromis to the existing trio, or should I replace the original three with a whole new bunch? I've heard stories of new chromis additions being killed by the original shoal, but I wanted some input from the local gurus.

Thanks!
Derry