Help Managing Account

My Xfinity account has 7 email addresses associated with it. My primary plus 6 others. I am trying to delete one of the 6 others and add a new one in its place. The system will not allow me to make this change because my primary account does not have a mobile phone number attached. My mobile phone number is attached to one of the other 6 email addresses. I am unable to add it to my primary account and I am unable to remove it from the secondary account to which it is attached. Subsequently, I am unable to make any changes to my account. The Xfinity phone number and my Xfinity chatbot are unable to understand nor resolve the issue. How do I attach my mobile number to my primary account?