For example, let's say I marry Abigail. Then Pierre should be my Father-in-Law and Caroline should be my Mother-In-Law, and this should be reflected in the parenthetical note where you see "Girlfriend", "Boyfriend", "Fiancee", "Wife", "Husband". Marrying Maru would make Sebastian your Brother in Law, and Marrying Shane would make Marnie your Aunt. Some unique dialogue related to this might be nice, but wouldn't be necessary. It would just be fun to look in and see that Emily is my Sister-in-Law.