If your sister-in-law is married to your brother or sister, her nephew may be your nephew.
Otherwise her nephew is not blood related to you, But he is related by marriage to you and he is stort of newphew in law.
Yes.
The English language has no relationship name for the wife of your great niece or great nephew.
If your sister had a son, then he is your nephew.
Your nephew's child is your great niece (if a girl) or your great nephew (if a boy).
The English language has no special name for a nephew's wife and does not consider you to be related to you. You would simply call her "my nephew's wife."
You are your nephew's uncle if you are male, and his aunt if you are female.
Your mother's nephew is your First Cousin.
Either nephew or nephew in law.
Mother in-law
My sister's son is my nephew.
Nephew
Nephew.