Estelle "Slim" Williams, kids, mystery lady

Photo is of Estelle Ai Williams, nickname "Slim", (son of Jack and Winnie Williams, from Iowa) with some of his children. Photo was taken in Pocahontas, Iowa, probably around 1963. It is believed that the mystery woman on the left in the photo was a relative of Slim's, and it is said that she was from "down south somewhere". Guess that means somewhere south of Iowa or at least south of Pocahontas, Iowa. Any information as to who the woman on the left is, would be greatly appreciated.
People in photo include: Mystery Lady, Estelle's Children, Estelle Williams