iCloud 200GB Family Sharing

hi,

My Apple ID is the primary account on our Family Sharing. However we have purchased our own 50GB iCloud Storage plans under our own different Apple IDs.

How do I upgrade my iCloud to 200GB and share it with my family without them loosing their data that's already stored in iCloud under their own Apple IDs? What are the steps to transition them over such that they no longer need to pay monthly for their own 50GB and just share my 200GB iCloud storage plan?