I think that you call them your cousin in law because its pretty much the same concept as a sister in law... its your husbands cousin so it would be a cousin in law
Well, it depends how close you are to your husbands family. If you really want to know they are cousins-in-law.
Your cousin-in-law.
Your cousin in law
brother in law
Your brother would call your husbands sister by her first name. Or, "my (sibling's) sister in law.
Sister-in-Law
You would call your husband's younger brother a brother-in-law.
Mom
either your niece's husband, or your nephew, or your nephew in law, etc
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.
If you are close to your step-brother, or to his wife, you can call her your sister-in-law. If you are not close, you can call her your "step-brother's wife."
yes, they might be "distant" but their still cousins