I don’t expect to get one definite answer here, but Google can’t give me one either. Some websites say they’re your second cousin, and others say they’re your first cousin once removed. I’m trying to figure out some family tree stuff so I need to know the difference between the (groups of) terms.
Your grandmother’s sister is your grandaunt, and you use grand and great the same way you do for mother/father but with aunt/uncle.
So I think your fourth cousin twice removed was on the Thresher but someone may correct me.