If your GF is out of contract, I would just add a line to my account and select a family plan and get her a phone and port her number over. (If she still wants it).
If she is NOT out of contract and is with VZW, you can do an Assumption of Liabilty to bring her into your account and then you can choose a family plan and wait to get new phones. (This does not add time to either contract)
If each of you are more than 12 months into your current contracts, (that is if she is on VZW also) and have a base plan of $49.99 or more a month, each can upgrade now at two year pricing. You forego your NE2 discounts and each MAY pay an add'l $20 but you each could get your new phones now and THEN bring her into your account via an AOL. This will change your contracts dates two more years from date of activation.
I hope I did not confuse you too much.
Thank you very much for your post.
She is actually a Sprint customer right now so the assumption of liability wouldn't be in there. However I am more than 12 months through my contract and over $49, I didn't know this made me eligible for a 2 year renewal! When I select upgrade from the website, it shows new phones at full price, not two-year price.
I see that I can pretty much go for new phones right now, the only downside not having the NE2 discount?