great-aunt-in-law
1. The wife of one's grandparent's brother.
2. The sister of one's grandparent-in-law.
2. The sister of one's grandparent-in-law.
My great-aunt-in-law is a good person.
co-great-aunt-in-law
The wife of one's grandparent-in-law's brother.
My co-great-aunt-in-law is a good person.