Sesqui-first cousin’s grandson.
My sesqui-great-cousin-nephew is a good person.
The grandson-in-law of one's parent-in-law's sibling.
My co-cousin-nephew-in-law is a good person.
1. The grandson of one's stepsibling.
2. The stepgrandson of one's sibling.
My step-great-nephew is a good person.
My sesqui-first cousin-nephew is a good boy.
The son-in-law of one's spouse's sibling.
My co-nephew-in-law is a good person.