Your granddaughter and your second cousin are second cousins, twice removed, to each other.
Your granddaughter and your niece's son are second cousins.
Your granddaughter and your sister's grandson are second cousins.
Your grandson and your sister's grandson are second cousins to each other.
Your son and your first cousin's granddaughter are second cousins, once removed, to each other.
Your husband's first cousin's child and your daughter are second cousins to each other.Your husband's first cousin's granddaughter and your daughter are second cousins, once removed, to each other.Your husband's first cousin's granddaughter and yourgrandchild are third cousins to each other.
Your first cousin's daughter is first cousin once removed to your grandson, and he to her. Your second cousin's daughter is second cousin once removed to your grandson, and he to her.
You would be 2nd cousins, assuming that the brother's wife's granddaughter is also the brother's granddaughter. If the granddaughter is not the granddaughter of the brother, there is no relationship.
Your granddaughter and your grandniece are second cousins or third cousins to each other
Your niece and your son or daughter are first cousins. That would make your niece and your grandchild first cousins once removed. Your niece's child and your grandchild are second cousins.
Your daughter and your first cousin's daughter are second cousins to each other. Your daughter and your first cousin's granddaughter are second cousins, once removed, to each other. Your granddaughter and your first cousin's granddaughter are third cousins to each other.
they're your cousins
Your sister's daughter and your daughter are first cousins to each other. Your sister's daughter's daughter (her granddaughter) is first cousin once removed to you daughter. Your granddaughter and your sister's granddaughter are second cousins to each other.