Putting a group of fish together, and letting them grow together often works well.
If you get only the grammode 1st, (or almost any cichlid for that matter), let it get established and then try to ad another, your letting the 1st one acquire territory(as in the entire tank) this then spells disaster for anything you ad latter.
If you 1st add 2 cichlids, they will often divide the tank in half, then add a 3rd, overnight it's probably going to be dead.
If you want a bunch, add the bunch all at once or expect carnage.