iCloud

I have today found my late Mother’s ipad (Model MD512B/A). It has 15,000 photos on it which I would like to back up onto iCloud so that I can share with family/ they can view.

I cannot afford to lose these photos or make a mistake!

My mother’s iCloud has expired (I don’t know the password anyway), her email account is now closed.

So my question is:

Can I setup her ipad with my iCloud details?

Given there are 15,000 photos, can I make a dedicated folder for her ipad on my iCloud that is independent to my ipad and iphone so I don’t download her 15,000 photos when I’m uploading my ipad/phone (same for the family when they access it).

Anything else I should be aware of before I do this - good or bad?

Thank you in advance!!