I am on a family plan and recently bought the new iPhone 5 with my fathers upgrade. I am looking to replace his current 3GS with my 4s and take his iPhone 5. I was able to pre-order online and should arrive at my house on 9/21. Is it possible to move his current line to my 4s and my line to the new iPhone 5? I would prefer if I could do this online or over the phone vs going to an actual ATT store. Is this also possible and what does the process consist of?