Apple ID's: Seperate ID's for Media and iCloud - Keep, Family Sharing or Start Again?

Hi,

My mum and I have separate Apple ID's for Media/iCloud; with the Media ID being shared. This is historical from when it was just me with an ID and so gained iTunes purchases, and was shared later when she joined Apple and have continued to purchase from this. For some years we have had our own IDs for iCloud.

Summary of IDs:

A: Mine, used for iCloud for myself only

B: My mum's, used for iCloud for my mum only

C: Shared, used for Media/purchases for both of us

I am desperate to 'be rid' of ID C, the shared one. I'm over 30yo now and this has been active for well over 15 years, it is time that we divide and conquer. From what I have read you are unable to merge accounts, which would be difficult here as we both would still like access to C's purchases. Is Family Sharing an option here? Please don't just direct me to the Family Sharing 'How To' as it doesn't really help with this situation.

It's now only my iPhone that has C attached to it, but my mum's iPhone and iPad are. She would likely benefit more from the C ID.

What are my options, if any?

Thanks in advance,

Hannah