icloud family share plan

If you mean family shared iCloud Storage, each family member's storage is still under their own Apple ID and is accessed in the same way as if it was not being shared. See the following from Share an iCloud storage plan with your family - Apple Support

When you share a storage plan, your photos and documents stay private and everyone keeps using their own accounts with iCloud—just like when you have your own storage plan. You simply share the space available in the iCloud storage plan with your family members, so you only have one plan to manage.