your cousin
Nephews and nieces
It says what relation are your brothers nieces to you.... It could be your child or your niece also causes you can have two brothers and it may be the other ones kids. Or of course it could be your brother's new wife kid by another man making her no relation.
You would be a first cousin by marriage, in other words, there is no direct relationship between you.
Nieces are the daughters of your brothers and sisters. Nephews are the sons of your brothers and sisters.
Uncle if you are male and aunt if you are female.
Great-niece.
Second Cousin
your 2nd niece...!
Your mother's sister-in-law is either the wife of her brother (your uncle), or your father's sister (your aunt). The niece of your uncle's wife is not related to you, unless she is you, your sister, or a girl cousin who is the daughter of another of your mother's brothers or sisters. The niece of your father's sister is you, your sister, or the daughter of another of your father's brother's or sisters. If your father's sister is married, she may have nieces who are the daughters of her husband's brothers or sisters. Those nieces are not related to you.
My father always made sure he remembered his nieces' birthdays.
Your brother's daughters are your nieces
Your borther-in-law's children are your nieces and nephews. You are their uncle or aunt, as is your spouse.