Your husband's brother's wife's niece may be the daughter of one of your husband's brother's siblings. That could make the niece your daughter, or your niece through your husband and another of his siblings. On the other hand, the niece in question could be the daughter of the brother's wife's sibling. In that case she is not related to you at all.
No. Your wife's niece is also your niece, but the husband of the niece is not related to you or to your wife.
either your niece's husband, or your nephew, or your nephew in law, etc
that would be your niece or if you want to be fussy then your niece in law!
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.
Technnically, she is not related as you do not share a common ancestor. She would refer to you as Aunt and she is your niece. Whether he is your first, second or fifth husband, his niece is your niece while you are married to him.
Great grand niece
great niece
You aren't related. You do not share a common ancestor.
Your niece's child is your great niece if she is a girl, or your great nephew if he is a boy.
You and your father's niece are first cousins.
Your niece's grandson is are your great-grandnephew.
Your niece would be your mothers granddaughter.