Hi, I want to buy a phone for my daughter. Unfortunately she is not able to upgrade her phone for a discount. I have a separate account and I am able to fully upgrade for a discounted price. This might sound stupid, but would I be able to upgrade the phone on my account and then give it to my daughter and have her activate it on her account? Will I be able to go back to my old phone and plan? My son has AT&T and it's easy for him because he uses one of those micro-sim cards.