If your niece's is by your sister but the brother is by your sisters new husband & another woman there would be no blood relation. If not then he's the nephew
He would still be your brothers son, or your nephew.
Then he must be your nephew, the son of your sister or your brother.
It says what relation are your brothers nieces to you.... It could be your child or your niece also causes you can have two brothers and it may be the other ones kids. Or of course it could be your brother's new wife kid by another man making her no relation.
Your borther-in-law's children are your nieces and nephews. You are their uncle or aunt, as is your spouse.
Nephews and/or Nieces
Uncle if you are male and aunt if you are female.
Second Cousin
Great-niece.
Your brother's wife's kids would be your nieces or nephews.
Your brother's daughters are your nieces
Nephews and nieces
your 2nd niece...!
I can give you several sentences.My nieces are coming for a visit.Are those girls your nieces?Nieces are the daughters of your brother or sister.
Nieces.