Doug,
All I can suggest is that you rearrange our tank so that established territories no long exist. This may be a huge job given the size of your tank
If this was my situation, I might even add the two tangs to your sump with the CCB while reaquascaping so they are all equally freaked at the whole episode. Once back in the display tank, there's a good chance everyone will have bonded during the crisis.
Actually had a similar situation a few weeks ago. Had a lone blue/green chromis in my 120g for ages, though there were other fish in the tank, just not chromis. Anyway, two fish died during a tank crash, and another fish was about to be sold because it was eating my snails. Without the snail eater, I thought the lone chromis would be lonely, so I thought I'd bring home some chromis buddies
Man, was that lone chromis ticked at the new ones
I had no idea it would display and chase the four new chromis all over the tank. This went on for a couple of hours, and slowly the original chromis began "tolerating" the new guys. Had to tear down the tank that afternoon to remove the snail eater, but left the chromis in the tank while reaquascaping it. They are all now thick as thieves
Can't wait to get one of the coral beauties I've been eying at the lfs. This should be a breeze to introduce it
