Sharing 200GB iCloud+ storage with family members

I am the organizer for our shared "Family" stuff on Apple. There are three members in the family. I keep getting messages that my iCloud 5GB is close to full. It seems to be mostly messages.

My husband, on his own, purchased the 200GB iCloud+ for backups a while ago. I have no access to that: Why?

Is there a way to make that larger iCloud into a family version and thus open it to all three of us?

[Re-Titled by Moderator]

Original Title: iCloud Sharing options