How to change a secondary user name without changing the password

I have a Primary account ID, and three secondary Users/email addresses.

I'd like to change the spelling on one of the secondary addresses, without changing the password.

I'm aware of how to change the password through 'Account and Identity', but the email line in the utility (just above the line to change the password) doesn't seem to allow editing the actual name of the User; even though an Xfinity Agent said that it would.

I know I could remove the User altogether, and setup a new User, but when I've tried to do that, the system won't allow me to because I need to use the same phone number, and it says that the number is already associated with the Primary Account.

Any help will be appreciated.

Thanks much.