iCloud Storage
Can i share icloud storage space through family sharing?
Your data doesn't migrate; It is really more of a shared billing arrangement. You each have your own storage up to a total of 200 GB but have a single billing. I haven't tried it but I don't think it needs to be the admin that does the sharing. Have your wife try the instructions in the "Share a storage plan with your existing family" section of Share an iCloud storage plan with your family - Apple Support
If that works then note the following from that same link:
If a family member is already paying for their own iCloud storage 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.
