The mother of Grandpa Ming (and of Grandpa Ming's brother) appears on Todd "Scoops" Ming's family tree in "The Ordinary, Extraordinary Botsfords". The tree indicates she is the grandmother of Grandpa Ming's son and daughter (Todd's parents Mr. Ming and Mrs. Ming, brother and sister) and Todd's great-grandmother.
She may be the wife of Great Grandpa Ming, who is the father of her 2 sons.