Donna is the daughter of Donnetta.
Donnetta is the granddaughter of Donnetta's sister, Donnita. Donnita has never met Donna. Donnetta is the _______ of Donna's mother.
Found in the Mindstretch Calendar by Terry Stickels
Donna is the daughter of Donnetta, and so:
Donnetta is Donna's mother.
Hence, Donnetta is the (name) of Donna's mother.