Jake Long American Dragon Season 4

This season's explanation of what happened to Rose's twin sister, could be that some characters discovered that their parents were going to have a daughter destined to be a warrior who will help to kill the magical creatures and because of that they tried to capture her unaware that she had already been taken from her parents and they captured her sister. With them presenting the real one to the group to convince them to release her. And still Rose would be more useful this season because since the characters sometimes have to face the magical creatures (which are bad) and with the free access that she could have the bases of the hunter's clan, she could be more useful in missions.