This method is all over the Verizon forum but didn't want to spread the word until I was sure it worked.. I did it though and it was surprisingly easy!!


Background:
I have 5 lines on a family plan, 2 iphones, 3 basic phones
My line (primary) is the only one with grandfathered unlimited data, my wifes phone has 2gig for $29 (purchased hers post unlimited era)
Verizon is not forcing anyone to go to the Share Everything plan.. If you are on a old plan (with unlimited) and want to upgrade they say you can keep you're old plan but the unlimited data has to switch the the tiered data plan $29-2gig, $39-4gig.. ect

SO:
I transferred an available upgrade from the kids line to the wife's line and ordered the IP5 on her line.
(could have used the kids line but transferred to my wife's just for ease of not starting another data plan and then later removing it)

When it came in:
DO NOT TURN PHONE ON (Once phone is on sim card is married to assigned phone number)
Get on verizon.com, and "activate/switch" phone
switch IP5 to line with unlimited data (type in IP5 MEID and SIM# that are provided on you receipt)
Turn on IP5 and it will marry to unlimited lines phone number and you're done

So what it really comes down to is as long as you don't change the contract for the line that has unlimited data, you keep it... If you already have a family plan with an available upgrade you've got it made in the shade.

But I've read of a few people that add an additional line ($10 for additional line and $29 for 2gig on old plan) and order the IP5, then transfer IP5 to unlimited line and put a basic phone on new extra line and cancel the data plan.. So then you are only paying an additional $10 a month and have an extra back-up phone.... Can't confirm it that works

Good luck!