Originally posted by: yukichigai
Sister-in-law.
Nope. Your sister-in-law is either your brother's wife, your husband's sister, or your husband's brother's wife. Your sister's husband's sister is none of these. She is nothing in direct relation to you, only in relation to your sister. Here's a clue: your sisters and your sisters-in-law are your children's aunts. The woman in question has no relationship with respect to your children.