How can I share iCloud with my family but have the photos and videos not be visible on my iPhone or in my photos main folder?

my son wants to be able to take photos and videos with his iPhone and edit them with iMovie on our Mac desktop. The Mac desktop has a photos album for him. I want to keep all of his photos and albums separate from mine. how do I do this with icloud? And when I use the desktop photos app, I can see his photos and videos on the main photos library. Is there ant way to separate his stuff completely but still give him iCloud ability and be able to use my iMac for editing?