icloud – 2TB family plan – want to move GF to her own plan

I have the max 2TB plan. My GF is part of my plan. However (both photographers) we’re maxing out the 2TB limit.

Instead of paying an ungodly sum for the Apple+ (which we won’t use) to get the extra 2TB – I’d rather just sign her up for her own 2TB iCloud storage.

How can I accomplish this, and move her 350,000 photo over to her account?

Thanks!
🙂