They are sisters in law.
Your sister's husband is your brother-in-law.
He is brother your brother in law.
Your brother would call your husbands sister by her first name. Or, "my (sibling's) sister in law.
You would call your husband's younger brother a brother-in-law.
Brother-In-Law means a wife or husbands brother and its your husband or wife's brother
There is no common ancestor, so you aren't really related. Related by marriage is one way to describe the relationship.
These people are not related either by blood or by law. There is no name for their relation.
brother in law
yes
Sister-in-Law
You call your husband's senior brother simply a brother in-law. There is no difference whether he is a senior brother or a younger brother he remains your brother in-law.