You need to figure out who's an account manager on each plan. If you are one on the old plan you're set for that one, but will need someone from the new plan that is an account manager as well. They will be able to get the approval to remove you from the old plan (if you're not one) and to add you to the new one.
It would be the Account Owner not the Account Manager who is capable of authorizing Assumption of Liability transfers.
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.