A new login technique is becoming available in 2023: the passkey. The passkey promises to solve phishing and prevent password reuse. But lots of smart and security-oriented folks are confused about what exactly a passkey is. There’s a good reason for that. A passkey is in some sense one of two (or three) different things, depending on how it’s stored.
Password managers are also updating to allow login with passkeys. I would give each family member a physical key that unlocks the rest. Since there are multiple, someone losing one isn’t a big deal and access can be revoked.