According to People magazine, Dakota Fanning was offered the role of Jane. This appearnetly was being worked on back in January.
Yes she was in New Moon and was a part of the Volturi who was Jane.
Yes she was in the 2nd Twilight movie, New Moon. She played one of the twins in the Voltori Guard, Jane. At first I did not think that Dakota could pull off Jane since Jane comes off as hard and cold and most of things I have seen Dakota in where the opposite. But she really did an awesome job portraying Jane and she looked just like how I imagined so 5 stars!