Change icloud alias to non-alias and use that as AppleID
"You can only add the @icloud.com address… - Apple Community
Ref error: "You can only add the @icloud.com address that is already on file in your account."
I get the above error when trying to change my appleID to an @icloud.com alias, which is "on file in my account" but as an alias. The previous discussion "says you cannot use an iCloud email alias as the primary AppleID email." This seems to imply that there is an icloud.com email address "on file" that is not an alias. Okay, so how do I replace that non-alias icloud.com address "on file", with the my alias icloud.com "on file" so that it is no longer an alias, and instead is the email that can then be used as my AppleID.