Your sister-in-law is either the wife of your brother or the sister of your wife.
A niece of the sister of your wife may be your daughter. If not she could be your wife's niece too, as the daughter of one of your wife's other siblings. A niece of the sister of your wife could also be the daughter of your wife's sister's husband. In that case, she is not related to you.
The niece of your brother's wife could also be yourdaughter or the daughter of another of your siblings, since your brother's wife is your daughter's aunt. If the niece of your brother's wide is the daughter of the wife's sibling, then she is not related to you.
Your niece and your daughter are first cousins. Your niece's daughter and your daughter are first cousins, once removed.
Your niece and your daughter are first cousins. Your daughter and the daughter of your niece are first Cousins, once removed.
Your daughter and your niece are first cousins. Your daughter than your niece's son are first cousin's once removed. Your daughter's child and your niece's child are second cousins to each other.
Your daughter and your niece are first cousins Your daughter and your great grand niece are first cousins, twice removed.
Your great great niece is the granddaughter of your niece or nephew. Your daughter and your niece or nephew are first cousins. Your daughter and your great great niece are first cousins, twice removed.
Your daughter and your niece are first cousins. Your daughter and your niece's daughter are first cousins, once removed.
Your daughter and your niece's daughter are first cousins, once removed.
You and your mother's niece are first cousins to each other, so your and the niece's daughter are fist cousins, once removed.
Your niece and your daughter are first cousins to each other.
Your son and your niece are first cousins. Her daughter and your son are first cousins, once removed.
Your daughter and your niece are first cousins. Your daughter than your niece's son are first cousin's once removed. Your daughter's child and your niece's child are second cousins to each other.
cousins