Yellow vs Purple Tang

This is a common question but I am looking for an answer to my situation. I have a couple clowns, goby, fire shrimp, hawk, filefish and Purple Tang that have been in the tank for quite a while. I recently added a Yellow Tang that had been quarantined for a while. As expected, the Purple was not pleased and did his best to kill him. They are similar size. I have removed the Purple and moved him to Q in hope the Yellow settles in. I also have a Blue Hippo and Copperband Butterfly on the way. I am trying to figure out the best way to get them all somewhat happy. I understand they will fight for territory and such. Its a 125G tank. Please dont say the tank isnt big enough. Its fine, i had all these fish successful in the same tank before Brooklynela wiped it out. These would be the last of my fish to get it back to where it used to be. Just wondering when to put Purple back and when to add the Hippo and CBB. The other thought was to get an Idol instead of the CBB. I know Tangs tend not to do well with Butterflies. Any help would be appreciated!!