Can you please be more specific on the circumstances behind the question? Is it his child, his niece, not related? Is the child born or unborn? Is the couple together or separated? Has he gone to court? If so what is the custody arrangements?
Your niece's brother is your nephew.
Your nephew's sister is your niece.
Your niece.Your brother's daughter would be your niece and you'd be her uncle or aunt. Your sister's daughter would also be your niece. If your sibling had a son, he would be your nephew.
Niece is to nephew as sister is to brother.
Nothing. Your niece in law. Your brother in laws niece.
Your brother or sister's daughter is called 'your niece.'
sisterNo it would be Niece is to Nephew as Sister is to Brother. Niece and sister are both female, nephew and brother are both male.
Your wife's brother's daughter is her niece and your wife is her niece's aunt. Although you have no genetic relationship to your wife's niece, by convention your wife's niece is considered to be your niece and you are her uncle.
Assuming that you are a female and that your mother actually has a brother, then yes, you are your mother's brother's niece.
The English language has no word for your brother's daughter other than "niece."
Your brother's daughter is your niece. Her daughter is your great niece.
Your brother's daughter is your niece and his granddaughter is your great niece.