My upgrade is in January 2013 (I can't wait that long!!), while a family members of mine (who shares a plan with me) is on December 2011. However, she is fine with her phone, and would have to pay for tiered prices anyway. Can I use her upgrade on my line, and still keep my unlimited date? I am trying to find a way to get the Bionic/Prime/GS2/Vigor without paying 600+ dollars off-contract. Thanks.