Dwarf angel..adding one..when you already have one..can it be done?

I would love to hear some knowledge or tips and tricks..I originally always wanted a Bi color angel..as fate had it without explaining the whole story..I got a Coral Beauty from the fish store as a credit for another fish. I love to coral beauty but my original plan was a couple of clowns a bi-color angel and maybe one or two others..I definitely want to have one!!! I need one..anyhow..I have a FOWLR only at this time im new..its 55 with two small clowns the beauty and a tiny yellow tang ( tang police begone) I have plans for a 120 or larger in the next couple of months and I have a 70 gal backup that i picked up....I dont need tang advice..please..but would love some knowledge about ways I could try this and pull it off..rumor has it sometimes you can take the first angel out for about a week and then re introduce him the day you get the new one..and perhaps move some rock..anyone care to share or suggest..Id love to hear from the experienced ones..your expeience doesnt have to be with dwarf angels maybe you added tangs or whatnot..can anyone help me out here?!