Wiktionary
stepgrandmother
n. 1 The stepmother of one's mother or father. 2 The mother of one's stepmother or stepfather.
Usage examples of "stepgrandmother".
And he sometimes listens to his stepgrandmother Annette, who has reincarnated in more or less her original 2020s body after spending some years as a great ape, and who seems to view him as some sort of personal project.