The term "mother sister" typically refers to the relationship between a person's mother and their aunt, who is the sister of their mother. This means that the mother and sister share the same parents and are siblings. In a broader sense, it can also highlight the familial bonds and connections within a family tree, emphasizing the importance of maternal lineage.
Your mother's sister would be her great aunt.
Her aunt
uncle.
Your mother's sister is your aunt. You are here niece (if you are a girl) or her nephew (if you are a boy).
Your son and your mother's sister are in a "Great Nephew/Great Aunt" relationship.
Your mother's aunt's husband's sister is your mother's aunts sister-in-law but is not related to you. Her son is not related to you either.
She would be just your sister's Mother-in-Law, but no special name exists for your relation to her.
Your son and your mother's sister are in a "Great Nephew/Great Aunt" relationship.
Your mother's sister's children are your 1st cousins.
The relation of the mother;s sister to daughter is niece-aunts.
Your mother's sister is your aunt. You are her niece (if you are female) or her nephew (if you are male).
Your mother's sister's husband's sister is your aunt's sister-in-law, but is not related to you. Here's why: Your mother's sister is your aunt. The sister of a woman's husband would be her sister-in-law. In this case the woman is your aunt. So your mother's sister's husband's sister would be your aunt's sister-in-law.