Does anyone have suggestions on verbal ways to authenticate family members, for example, on the phone?
Have every family member scan that code for use with the TOTP authenticator of their choice on their phone and/or tablet and/or watch.
When you are talking to someone who purports to be a family member you ask them for the family TOTP code and check to see if they give the same code that your TOTP authenticator on your phone or watch is showing.