My girlfriend and I are both on Verizon. She has a 4S and is upgrade eligible, I have a 5 and am not. She is not interested in having the latest and greatest, so she offered to get a 5S at the subsidized price and extend her contract to do so. Could we subsequently swap phones (she gives me the 5S, I give her my 5), without extending/affecting MY contract and and MY upgrade eligibility for next year? We have completely separate plans.