Not sure if they'll hit it off. I'll just share with you my experience with clowns. I added 1 black and white percula along with two true perculas at one time to my 90 gal. They all got along, but it was obvious that the black and white perc was the boss. He never actually bit or nibbled on the others, but he'd chase them every once in a while when I fed them. I added a tomato clown about 4 weeks later to the tank and he fought constantly with the black and white perc. The tomato and the true percs never had a problem, but the tomato and the black and white always did. I then added a sebae clown about 3 weeks or so after that and the black and white perc started to fight with him. The tomato and the sebae had a few brawls, but nothing to talk about. It was basically just a war now between the sebae and the black and white perc. Eventually I took down the tank do to hair algae and gave the fish away to a friend. Now what I've experienced with clowns doesn't necessarily mean everyone else will. All fish are different and I guess it's just a chance you got to take. You may be lucky and not ever have a problem with adding clowns then again that might be all you will have (a handful of problems). I guess the only guarantee you'll have is a better success rate by adding all the fish at the same time, but then again, that is still no guarantee