Hello,
my 15 year old son is not able to leave the family iCloud of his father who just passed away. Additionally, he has screen time on and can’t download any apps etc. How can I get him to join my family icloud since no one can approve leaving the fathers iCloud??
Contact Apple Support directly, and describe this case to them.
The documented route starts with gaining access to the Apple ID:
… How to request access to a deceased family member's Apple accounts - Apple Support
Once that is available, the rest of the transitions (probably starting with disbanding the Family Group) can happen.
Leave Family Sharing - Apple Support
This if there is no legacy contact already established:
… How to add a Legacy Contact for your Apple ID - Apple Support
Leaving family icloud for another iCloud
