great-great-great-nephew

Sibling's great-great-grandson.

great-great-great-nephew.

great-nephew-in-law

1. The grandson-in-law of one's sibling.
2. The grandson of one's spouse's sibling.

My great-nephew-in-law is a good person.

first great-cousin-nephew

First cousin's grandson.

My first great-cousin-nephew is a good boy.

double-great-cousin-nephew

Son of their maternal first cousin’s child with the paternal first cousin’s child or double-first cousin’s grandson.

My double-great-cousin-nephew is a good person.