Like many have mentioned before its a difficult balance when you stock multiple aggressive cichlids in a tank, irrespective of the tank size.
Sometimes you get lucky and they all get along and you have a spectacular tank, which then becomes the envy of everyone, other times the alpha/tank boss decides he doesn't like company and slaughters everyone else.
It is great that you are listening to advise and understand that hyper aggression from one of these fish is a distinct possibility.
You have some beautiful fish & I wish you luck and hope you have a tank like I did in the past where they all lived in peace.