Family sharing; storage
In family sharing, what if a user is already sharing their storage, but I have the bigger 2T iCloud and want to share. How do I do that?
iPhone SE, iOS 15
Follow the steps in the support document you posted from in the section titled "Switch from your iCloud+ plan to your family plan" from one of the user's devices.
If a family member is already paying for their own iCloud+ plan, they can choose to switch to your plan or keep their own and still remain part of the family. When they switch to the shared family plan, they get a refund for the remainder of their personal plan. They can't keep their current plan and use the shared family plan at the same time.