I don’t have an answer for you.
Plain and simple: It can be a mess to try and manage the Apple IDs.
If you are locked out of a previous account then apparently you can’t even update the software associated!
Whether its purchased, or whether its an OS update. (I presume).
I refuse to call them email addresses, because the problem is that while at one time you had to have a current email address as your login, that really not at all true - they are User IDs. People get divorced, or change ISPs & thus change these.
Apparently too, if the ORIGINAL login is no longer valid ---> then where does the notification email go once you engage 2 step verification?
You are in a loop: better know your security Q answers, or have the email working, because they will refer back & forth to each other. You can’t get to one, without the other.