It seems that one cannot currently add multiple accounts to the 1Password app if they are part of the same Family. I maintain some other Family members' (kids, elderly) accounts, too, including personal vaults, if they have a problem. It makes sense for security purposes to keep these vaults personal by default and only access them directly when needed.
One can do this by logging into the web interface using the other member's credentials, which may be cumbersome, because switching accounts in the browser requires entering the account key (autofill does not work on purpose, as discussed elsewhere). It may also sometimes be more convenient to do so from within the app, which has features (e.g. better search) not currently available in the web version.
Are there plans to add support for multiple Family logins within the 1Password app?
1Password Version: Not Provided
Extension Version: Not Provided
OS Version: Not Provided
Sync Type: Not Provided