Your Aunt. With Aunts and Uncles there is often no blood relationship howerver they are still your Aunt or Uncle. With step families taking the role of step Grandman, Grandpa, Cousins Aunts and Uncles it is more of what the individuals feel comfortable with. If her name was Beth, you could call her Aunt Beth if you were comfortable with it or just Beth is fine. If they were step sisters before you were born and the family is close then she would be your Aunt since birth and no step class is really recognized. If you were older when the marriage took place then a first name is fine.
Your mothers sister is your Aunt
Aunt Aunty Auntie
Mothers sister is aunt and son is cousin so daughter wouldn't that be a niece
Your mothers husband would be your step father and you would be a step son or step daughter.
She would be your step-sister
Your daughter's step-sister would be your step-daughter.
Your mother's new husband is your step-father and you are his step-son or step-daughter.
Your moms daughter would be your sister, so your sister in law would be hers too.
No, you are not related to your stepmother's niece. However, if she has been your stepmother since you were a young child, you may have interacted with her niece as if you were related, and that is fine. You can even call her your cousin if you want to.
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.
You not related to that person.
In most cases, your sister's mother is also your mother, and her husband is your father. If you and your baby sister have the same father but different mothers, your sister's mother's father is your father. If you and you sister have the same mother but different fathers, your baby sister's father is your step-father if he is married to your mother.