Maid of Honor
Sydney is Frankie's sister and Hailey's sister that she never had growing up (as well as makeup artist, hair stylist, shopping buddy, etc.).
Best Man
Roman is Frankie's (not so little) brother. If you ask them to talk and close your eyes, you won't know who is speaking. He gets his love of golf from his brother, the best golfer he knows. Ask him about his swing.