Unfortunately, it’s not possible to change the address registered on an existing Premium for Family plan.
If you move, or enter the wrong details, you need to create a new account and subscribe to Premium for Family on that account. Don’t forget to cancel the plan on your old account 🙂
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.
Note: I'm not a Spotify employee.