Different clowns in a 90G

I have a 90G reef tank, with a 20G sump. It is running fallow at the moment due to an outbreak of ich (and potentially velvet). I lost a few fish, but managed to save the ones currently floating around in Cuprmine. One of the fish I lost was a tomato clown, who hosted in my rose BTA. The BTA is on the smaller size (about 3 inches across).

I also lost some anthias, which I have decided not to replace. Instead, I would like to get 2 x black & white ocellaris, and 2 x orange ocellaris. I have read that if you introduce them at the same time, to an appropriately sized aquarium, they should be fine. My question is, what do you think, is this a good idea, or just stick to 2 of the same species (color)?

Also, 2nd question (though I suspect I know the answer to this already). I only have 1 relatively small BTA, at one end of the tank. If you think it's OK to put different species of clowns together in a 90G, do you think only 1 BTA would cause an issue?

Thanks in advance,

Badger