Right missed that unless she join later in life and that she was a third year student was just to show she had been there three years, but who can say as we dont have details on their ages overall to make a judgement one way or the other.Except she tells Josy (when they first meet and Josy asks if she's a freshman or "freshperson" if you've been hanging out with Dany too much), that she's a third year student. So she must have just started staying at the mansion during that flashback scene.