Question: is nephew in law a thing?
Answer: Additional terms. A niece-in-law or nephew-in-law is the spouse of one's nephew/niece, or the niece of one's spouse. A co-niece-in-law or co-nephew-in-law is the spouse of one's niece-in-law or nephew-in-law. ... A fraternal niece or fraternal nephew is the child of one's brother.