When signing up for Premium for Family, you are required to submit personal data like a name and address. This data can't be changed. So if your account has been taken over at some point in the past, and you are seeing an unknown name, we recommend starting over with a new account.
No worries, if you make sure your music collection is stored in public playlists, you can visit your old account with your new account and grab all your songs from there. You can visit your old account by putting the following string in the search bar: spotify:user:username
Don't forget to replace username with your own username. Oh and by the way, If you want to use the same email address for your new account, you'll have to close your old account. You'll have 7 days to visit your old account and find your music there.
We hope you'd like to try this! It's a lot quicker than it might seem. Let us know if you have further questions.