Changing user ID Issue on Apple TV

I have various Apple TV boxes from Gen 1 to current version but the issue is the same for all.

I have verizon email that I have been using for years to sign on to my Apple TV box. Movie and Music purchases thru that ID thru the years as well. I will no longer be using Verizon as my provider due to a move so I will be losing the Verizon email permanently and it will become free for someone else to snag it.

TI also have and Apple Email that was created when I got my iPad.I am trying to change my Apple TV ID from the Verizon email thats going away to my existing Apple email which I have had for a while as well.

The apple link to change ID link will not let me do that because this is an existing account.

If I make up a new Apple Email account I can then login in with those credentials BUT it wont have access to the purchases made under the verizon email that is going away.

How can I change my ID and not lose all of my purchases?