In America I'm sure it would go against the law, but in other countries or places I have no idea. Don't marry your mother's sister's daughter.
Such a person would be your second cousin, and in most places marriage between second cousins is legal.
Niece. Your mother has children, you and your sister. So your mother's daughter is your sister. When she has a daughter, this is your niece.
cousin
Through marriage your step - sister's daughter is your step-niece!
Mothers sister is aunt and son is cousin so daughter wouldn't that be a niece
no....because she is a sister for you
Sister, but possibly only half sister if the baby and the father's other daughter have different mothers
If he is your brother in law then his sister is your sister in law. So your sister in law's daughter would be your niece.
Since your sister's husband's daughter is usually your sister's daughter, you are her aunt or uncle. If the husband's daughter is from a prior marriage (before he married your sister) then the daughter is not related to you. However, if the daughter is young, her father may have her call you and treat you as an aunt or uncle.
a step sister is the daughter of a man or woman that remarried to your mother or father that they had had in a previous marriage.
Your son-in-law is your Daughter's husband. His family are part of your extended family but while your daughter is an Aunt (by marriage) to the child and the child is a Niece (by marriage) to your Daughter. The child is no direct relation to you.
The relation of the mother;s sister to daughter is niece-aunts.