Scrooge spends Christmas Day with his nephew Fred and the Cratchit family, including Bob Cratchit and his son Tiny Tim.
Every day is nephew day.
It was his nephew Fred
To dine with them on Christmas Day
To visit his Nephew Fred on Christmas Day
Your nephew's nephew is the son of one of your nephew's brothers or sisters. He is your great nephew.
Your mother's (mom) nephew is your answer.
Your nephew's son is your grand nephew or great nephew.
Your nephew's son is your great nephew. Your niece's son is also your great nephew.
Your wife's nephew is your nephew and his son is your wife's, and your, great nephew.
The male counterpart of a niece is a nephew.
There is no official national nephew's and niece's week in the US. Nor is there a specific day in the year where niece's and nephew's are celebrated.