I have a large old black clown fish in a 120 gal. She just moved over from a 55 gal about three weeks ago. She is all alone currently. I have a small ocellaris, firefish, and pj cardinal ready to join her. Any suggestions on how it should go down? Should I add all three at the same time, isolate the old lady, add one at a time? The new clown is a quarter of the size of the old gal so don’t expect it to be an issue and the three new additions have been in quarantine for 5 weeks and are good friends. TIA.