Achilles Tang Issue

I have a powder blue that does good with grazing as a meal suppliment. He wont eat any macro or even the seaweed but he will eat some mysis though. Try some mysis with your garlic.
As I was reading the thread I wanted to say "Ask the lfs to babysit it for you for a couple weeks if you are really that hooked on your purple" BUT there is always one aggressive tang and the purple is your dominant one. My powder blue kicked my 8-9" Naso's butt soon as I dropped him in my tank. I was like what?!?!?! My naso died but I was more on the happy side that my Powder blue didn't die because I've always wanted one and heard they weren't hardy. I must've got the exception.
But, to the point, you should ask them to hold your purple to see if your achilies makes it. If the archilies lives 2 weeks, it'd be safe to say it'll be okay for them to sell YOUR purple.
I have seen professionals kill some achilies though so be extra caring. Your tank is all in what you want and if you want that achilies more, do it. I want a powder brown but I know my blue will be fighting him all day.
Moving rock work is temporary, if at all even working. Sometimes it'll work for a little but they'll still go back at it after the tank settles back down.
Good luck and Congrads on the new arrival!!