So I have an AT&T iPhone 5s that I bought last year. No upgrade available on my line. My brother who is the main account holder, and sister-in-law both have upgrades available on their lines (we're on a family plan). They both just upgraded their phones to Samsung Galaxy S5's not too long ago using upgrades from my mom and dad who are also on the plan. Is there a way for me to use my brothers upgrade during pre-order? I want to buy the iPhone 6 Plus.