That is difficult to say. Their niece could be your daughter. They could be your niece as well if they are the child of one of your siblings. Or there could be no relationship at all if there is no common ancestor.
Your wife's niece is also your niece, and her daughter is your great niece. It is to be hoped that you do not have a relationship WITH her, merely TO her.
great niece
Great grand niece
Your niece's child is your great niece if she is a girl, or your great nephew if he is a boy.
Your niece's grandson is are your great-grandnephew.
You and your father's niece are first cousins.
Your niece would be your mothers granddaughter.
You are her great-aunt/uncle. She is your great-niece.
If your father's brother's niece is really your father's brother's wife's niece, then there is no genealogical relationship. Otherwise, she's either your sister or your first cousin.
Your granddaughter and your niece's son are second cousins.
Your niece's son is your great nephew.He would be your grandnephew
Your Niece.