There are a few scenarios where it would be necessary for a policyholder to add an additional insured to their policy. You might need to use the additional insured option if you’re buying a home with your partner, but the two of you aren’t legally married. In this case, one partner would purchase the policy as the named insured and add the other partner as an additional insured. If an elderly relative dies, and they leave their home to three grandchildren (cousins from three different families), those three cousins would each need to be additional insureds on a policy covering the home.