1. The parent of one's stepgrandparent.
2. The stepparent of one's grandparent.
My step-great-grandparent is a good person.
My great-great-grandparent is a good person.
Great-great-grandparent's parent.
My great-great-great-grandparent is a good person.
Great-great-grandparent's parent.
great-great-great-grandparent.
The great-grandparent of one's spouse.
My great-grandparent-in-law is a good person.