The father 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 he is the grand-father of Grandpa Ming's son and daughter (Todd's parents Mr. Ming and Mrs. Ming, brother and sister) and Todd's great-grandfather.
He may be the husband of Great Grandma Ming, who is the mother of his 2 sons.