Looking back through the thread and seen some really good suggestions.....The White Cheek won't hold it's own against 2 somewhat aggressive tangs that are already established....I have tried this scenario on several different tank, and different Tangs, and the White Cheeks seem really passive.....My choice for a Tang to hold it's own would be either a Powder Blue Tang or a Purple I think would fair better.....A little rearranging also helps equal the playing ground.
The Fox face would be a good addition.....regardless of what the books might say, they don't pick at corals and such.....they are a good addition to a reef setup.
Angels can be touchy....I've always kept a Coral Beauty in all my reefs and alot of other tanks with no ill affects. I also keep a huge Bi Color angel, which does pick, but he's kept his menu to GSPs.......Chalk Basslets are another good choice, I also like Marine Bettas which are neat, but not very open till they get use to their surroundings......
Triggers were suggested earlier, and to much suprise there are several that are reef safe, and don't go after corals or inverts.....Cross Hatch being the top of my list....Some people keep M/F in the same tank.....Beautiful specimens......