Well my aunt is what I call my mother's brother's wife meaning we're not blood but that's normally how it works in most cases. Or at least with the first wife because my mother's other brother who remarried after his wife passed & I don't call her my aunt.
That will depend on what makes her your sister-in-law. If she is married to your brother, her daughters are your nieces. Otherwise there is no relationship.
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
There is no actual blood relationship. You would typically introduce her in that way, My son-in-laws's sister. Many refer to her as the sister-in-law.
Technically there is no relationship. When introducing her, you would refer to her as My daughter's mother-in-law.
The daughters of your sister are your nieces.
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.
Real sister, half sister, or step sister
sister in law.
Your sister's sister is your sister.
No relation whatsoever. You will be an aunt or uncle to your sister's child and your brother-in-law's sister will be the child's aunt, but that's as close as it gets.
Your mothers sister is your Aunt
You would call your sister's daughter your niece.