Porting a number at an Apple store?

I am going to try to purchase an iPhone 6 (not plus) on Monday. All of the AT&T stores in the area are consistently showing no stock, so I'm assuming I will have to go to an Apple store. Problem is, we are making some less-than-common changes to our plan, and were advised by AT&T to do it at a corporate store. My wife is currently on a family plan, and she will be transferring liability on her line to us, and adding myself as an additional line on the new account while porting a number over from Sprint.

I know that at an Apple store, we can buy a phone and add a line to the account. My question is, can they port numbers from Sprint to AT&T at Apple stores? If the answer is yes, then I'm all set, because my local Apple store has the phone I want in stock every time I check online. If the answer is no, then I could be in for quite a long wait.