Adding a line to UDP

A

AC Question

Hi - Looking for some advice if anyone could be so kind.

Wife and I just got married and want to join our phone lines together. My wife has a Samsung Galaxy S5 on a verizon UDP (Nationwide Talk 450). I have a Galaxy S4 and I am on a Verizon family plan with my parents/brother. My family plan is capped at 13GB data. Naturally, I would like to add a line/transfer my line to my wife's UDP account and be able to keep my existing phone number. I have read a bunch of articles on getting phone upgrades while keeping your UDP, but have yet to come across any current articles (which still have usable options) on adding a line to an UDP. I went on VZW website and tried to add a line to my wife's account there but it appears to force a selection of a fixed data plan. Are there any other options or am I out of luck.