Your sister-in-law's niece is not related to you because you have no ancestors in common.
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The above answer is true, but by marriage, that niece would also be your niece or your own daughter. This is because your spouse is blood/sibling related to his/her sister (your sister-in-law).
Your brother-in-law's neice may be your daughter or your neice, or unrelated to you.
Absoulutly nothing to you.
None lol
Your sister's husband is your brother-in-law. His niece is a child of one of his siblings, and is also a niece of your sister by marriage. There is no relation to you.
Your Aunt's niece is you (if you are female), your sister, or your First Cousin.
Nothing. Your niece in law. Your brother in laws niece.
Great niece
Probably your niece-in-law.
You are her niece or nephew (niece if female, nephew if male) and she is your aunt.
you would be her aunt and she would be your niece
You are their aunt or uncle and they are your niece or nephew.
Probably your niece-in-law.
He or she is your great-niece/nephew
Your sister's daughter is your niece and you are either her aunt or her uncle. The English language has no term for your niece's husband, other than calling him "niece's husband."
it could either be your brother/sister or cousin