Try not to mix ur clown species, Your Maroon may or may not attack ur occ/perc, or it may just take it as a pair.
why risk the health and well being of a fish knowingly. Skip the Maroon, ur ocell may host in ur BTA
as far as ur Tang, he's fine, and just keep ur BTA away from any soft corals, it will wander at first, find a spot and settle in.