One vault, three kinds of space
Everything you add goes into your personal vault by default. A family space is for the people you live and plan with: the health insurance everyone is covered by, the house papers, the car documents, the children's certificates. A group is for anything else you share, such as flatmates splitting rent or siblings looking after a parent's paperwork. When you add a document, choose every place it belongs.
Shared payments and reminders
Payments in a space show up on every member's calendar, and each member's own app schedules their reminders. When rent or a premium is marked paid, everyone sees it, so nobody pays twice and nobody assumes someone else did.
Nobody is added without saying yes
A person joins only by accepting their own invite, or by asking with a join code and being approved by the creator or an admin. Before a key is shared, the approving device seals the space key to the new member's personal key, and you can compare a fingerprint code to confirm it is really them.
Leaving and removing, done properly
When someone leaves or is removed, the space gets a new key and everything in it is re-encrypted. Files they uploaded stay in their own Google Drive; files others uploaded stop being shared with them. Nothing added afterwards is readable to them.
Family members without the app
Young children and elderly parents often do not need their own account. Add them as managed members of the family, keep their documents and payments in the space, and their names stay encrypted with the space key.