Alright so here's the situation: I'll be buying an iPhone on Friday as an existing At&t customer. I'd like to go to the Apple store, buy the phone, add the data plan, and be on my way. However, I am on a family plan. And the other phones in my plan are also eligible for an upgrade. Thus, it looks like I'll have to go to an At&t store to pick up the other phones, right? My question is: Can I upgrade myself to the iPhone now, sign the additionally two year contract, add the data plan...then upgrade the OTHER phones at a later time?