Problem recovering Office 365 Family Plan owner account when original email account is not longer accessible.

I purchased and set up personal Office 365 Family Plan over 10 years ago using company email and authentication using company provided RSA token. When set it up, I used this for the owner administrator account and created another non-owner account that I have been using since then.

I retired from that company 6 years ago and have not had a reason to use the owner account since that time, and have been using my non-owner account since that time.

Recently, I wanted to create a new account for my son and realized that I had not changed the owner account to work with a different authentication method.

Since I could not login to the account, I could not change the email address and login authentication method, and was directed to use the account recovery form.

When I received instructions in an email, I set the account to use my phone number as the authentication method, but after connecting using that method, I found that I created a new free account instead of recovering the owner account for my Office 365 Family Plan.

The account is still being paid for using my credit card and I last paid the annual subscription fee according to my credit card records on 12/4/25.

How do I proceed with recovering the owner account that I need use for adding an account for my son.

Thanks,