A Microsoft file hosting and synchronization service.
We’d really like to keep each person’s files separate. Since the Family plan supports up to five users, we assumed each person would get their own OneDrive space with isolated sync folders.
Yes, if you share Family with them and they sign into office using their username and password
A family subscription is meant to be shared with up to 5 Microsoft accounts, not shared with others using the same log in.
If you have not shared the subscription with them,. go to https://account.microsoft.com/services/microsoft365/details?startSharing=true#sharing and share Microsoft 365 with them. They will then sign out of office and OneDrive that is using your address and sign in with their address.
Microsoft article on family sharing: