Provided he can still log into the account and play the game, I'd just get a new email address (like with Gmail or something) which would be specifically for RS.
Then go through the account migration process, using the new email for the Jagex Account.
Once completed, the account will be set up, and have a new email to use for the account and proceed on fine.
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If he cant log in atm and needing to get that solved also, he'd have to do an account recovery with a new email address. once successful, it will have that email applied, and then can go through the migration process.
Can I turn in a paper without citing all sources?
"No."[1]
1. William Shakespeare,
Hamlet
, Act III, Scene 1, line 96.
02-Jun-2023 00:41:38