Nibling-in-law (only spouse's nibling).
My nibling-by-marriage is a good person.
1- Nibling's spouse.
2- Spouse's nibling.
My nibling-in-law is a good person.
1. The child-in-law of one's sibling.
2. The child of one's spouse's sibling.
My nibling-in-law is a good person.
My nibling-by-marriage-in-law is a good person.