Nephew and daughter-in-law First, your sister's son is your nephew, and then your nephew's wife is your nephew's wife.

In real life, your nephew's wife is your junior. You can call her by her first name or by her first name, which is more cordial.

To sum up, my sister's son is my nephew, and my nephew's wife is my nephew's wife. In real life, you are her elder, and you can call her by her first name or nickname directly.