Your husband's cousin's sister is also your husband's cousin. You are not related to your husband's cousin.
No relation...lol
As there are no blood ties there would be no relationship.
Your mother's sister's children are your 1st cousins.
Your daughter and your sister's child are first cousins. Your daughter and your sister's grandchild are first cousins, once removed.
Your sister's son and your daughter are first cousins to each other.
Well, it depends how close you are to your husbands family. If you really want to know they are cousins-in-law.
The common ancestor is your parents. Your children and your sister's children are first cousins. Your grandchildren and your sister's grandchildren are second cousins. Your great-grandchildren and your sister's great-grandchildren are third cousins.
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
Your son and your mother's sister are in a "Great Nephew/Great Aunt" relationship.
They would be cousins, once removed.
Your daughter and your sister's son are first cousins to each other. Your sister's son's daughter (her granddaughter) and your daughter are first cousins, once removed.
Your cousin's sister is also your cousin. Your first cousin's children and you children are second cousins. Your second cousin's children and your children are third cousins. And so forth.