I looked at the other post, but I don't have the option of creating a faux email account on Comcast. The Comcast email I have dates back to the 90's. I no longer have any other Xfinity/Comcast service, so I don't have a Subscription of any kind with them. It seems that you have to have some kind of a subscription to add email accounts or to get any Support from them. I guess that makes sense.
I guess so. In most cases resolving an "this account already exists" annoyance is easily determined and becomes obvious in retrospect, but it seems you're already ahead of me in researching those causes. Basically you have to exhaustively examine each and every one of the accounts and related services in Settings > Accounts to determine the source of the conflict.
Most likely, you have many such accounts so examining each one can be a time-consuming chore. Very briefly stated though, "this account already exists" means what it says and I have never failed to determine the reason. You just have to determine what and where.
You don't want to exacerbate that tedium though, which brings us to:
So, I think the only other option is to change my Apple/iCloud Account ID to another email address. It doesn't look like it is very difficult, but can you tell me what the ramifications of that are?
My initial reaction is don't do it. Of course you can change the email address associated with your Apple Account any time you want, but the ramifications will extend to every Apple device, product, or service you're using. If you have many, it's a major PITA. And I don't think it will help.
I think I have created some iCloud email addresses in the past, but I don't recall what they are. Is there a way to find them, ...
Probably. Start with https://iforgot.apple.com/ and see how far you get. I cannot provide instructions more specific than that because Apple is characteristically tight-lipped about the means by which they can recover lost or potentially forgotten Apple IDs.
To Apple, "you" = your Apple ID (Apple Account). Having more than one is like having a clone of you, and if you're like me it's difficult enough to manage just one 😆
... or should I just create a new one and change my Apple/iCloud Account ID to that email address?
I believe creating a new one won't fix the problem, but you can certainly log out (sign out) of one and log into another. The more you have, the more tedious it gets.
As for Contacts stored locally "on my Mac" or whatever they call it these days, they are probably still present. Examine the Contacts app's settings to determine if they are hidden or not.
