The grandchild-in-law of one's parent-in-law's sibling.
My co-cousin-nibling-in-law is a good person.
To suckle or to suck on smaller things or small body parts like toes, nipples or finger tips.
I want to nible on your nipples
Nibling-in-law (only spouse's nibling).
My nibling-by-marriage is a good person.
My nibling-by-marriage-in-law is a good person.