Who is Nancy Rufford from The Good Soldier and what is their importance?

Nancy Rufford is Leonora Ashburnham's ward. She needs a guardian because her mother is an alcoholic, and her father is abusive. Nancy comes to live with the Ashburnhams when she is thirteen-years-old, and she adores Edward Ashburnham as the father figure she never had. Over time, however, her adolescent feelings eventually turn into romantic love.