Family share; changing countries on family accounts, don't want to add billing info

Hello,

I have moved from the USA to the UK. I have successfully transitioned my account to the UK, but in attempting to transition the various family accounts I am having issues. The system seems to be set up so that I need to enter a credit card to finalize transitioning an account. I do NOT want my kids to have access to credit card information which is why I like the family sharing feature. How do I update an accounts location without adding my credit card information?

Peter