chances are they wont get along. if the tank is huge, and they can stay out of each others way, maybe...but it is very risky to add more then 2 clowns per tank
there is a good chance the female (largest clown) will kill the new ones.
the best shot you have is to get baby ones, since they wont have matured into having a gender yet, and even then, the one that matures probably would never develop a gender
(all are born genderless, and the most dominant becomes female (largest), second becomes male (second largest) rest stay no gender