Who is Rachel or Sparrow Hawk Stonehorse from Dalva and what is their importance?

Rachel Stonehorse (Sparrow Hawk) is Duane's mother. She was hired one winter to help Paul, Wesley, and grandfather with their hunting cabin. Wesley immediately fell for Rachel, and he ended up impregnating her. To avoid a fight between the brothers, Grandfather sent Rachel away. He did, however, help care for Duane throughout his life.