I prefer keeping custody of my seed phrases myself, and only a trusted family member knows where it is but cannot access it easily. If I'm gone or something, the family member can have full access to it.
The safest way is to only give them instructions how to access seed phrases but they wouldn’t get the whole instructions while I still am alive. Maybe a lawyer will hold the last key piece of the instructions so that he can deliver it to my family when I am gone.
In the meantime, completely entrusting your seed phrases to someone even if they are a family member seems risky still. You never know what a person can be when money is involved.