Mackenzie Matthews is Riley's little sister and Auggie's big sister. She is a well known dancer, but her parents don't know because they mostly pay attention to Riley and teaching her about life. That means that they have never gone to one of her performances. The only one that's ever gone to all of her performances was Auggie and that's only because their parents think their in his room.And she's been dancing since she was 4! Will the Matthews soon know how Mackenzie feels and start paying attention to her, or will she always be the forgotten child.