Great Grandma Botsford is the mother of Bampy Botsford, Mr. Botsford and Ms. Botsford. She's the wife of Great Grandpa Botsford (also the father of Bampy's Mr. and Miss. Botsford), the paternal grandmother of Tim Botsford, the grandmother-in-law of Sally Botsford, the adoptive paternal great-grandmother of Becky Botsford and the paternal great grandmother of TJ Botsford. She's depicted in Becky's family tree in "The Ordinary, Extraordinary Botsfords".
Like Grandma Botsford, her own parentage is not depicted on the tree.