If you want to keep the cheery personality you could give her a younger sister or brother, or even just a younger friend or relative she's really close too and who was also effected by the tragedies. People in her situation will some times try really hard to keep a happy face on as to not have other people worry about her and to be a strong influence in the younger persons life. Or maybe she could have been trying to stay happy for her mother, then after she was killed she didn't know any other way to react to the situation. But I do agree that having more than one little girl ruins the novelty of the first one, depending on who would show up first.
