I know they treat each line separately but I would still like to just have the person who wants the new line take over the account of the other. It basically amounts to changing the number, "upgrading" the phone and a new contract. I'm not bothered about the early termination fee that would be incurred by canceling the one line, but that one still has the original unlimited data plan that would be nice to keep intact. Is there any way around this? Family member One needs to keep her phone number, member Two is OK with a new number. The only thing I can think of is just to have member Two just take over the account then request a number change - but then how could member One get the number back without porting it over?