Cousin
your second cousin
bhagina
Your sister's daughter is your niece, her granddaughter is your "great niece"... or you could just call her by name.
you call her your daughter's husband's sister
Your daughter is your sister's niece. Your daughter's son is her great nephew.
You would call your sister's daughter your niece.
Evelyn had her fathers baby making the baby both sister and daughter
Let's see if we can unravel this. Your sister's husband's father's brother is your sister's husband's uncle. The uncle's daughter is your sister's husband's cousin. There is no relationship to your sister, unless your sister wants to call her a cousin-in-law. To break it down to its simplest terms: She is your brother-in-law's cousin and no relationship to you.
sister friend
Niece
Your sister's daughter is your niece.
Aunt