Hi. I was wondering if I could be put down as an authorized user for an AT&T account that my mom, dad, and sister are on - even though I am not on the family plan itself and have a different mailing address (despite same last name).. I am over age 18 and have my own personal plan with AT&T and already upgraded my phone with an iPhone 4 pre-order. I wanted to go in and get an iPhone 4 for my dad at an Apple, AT&T, Best Buy, or Radio Shack. All 3 of their lines are eligible for a discount iPhone 4 but just my dad wants it.