You are the great aunt/uncle of your sister's son's daughter, and your sister's son's daughter is your great niece.
she would be your grandmals sisters sons daughter =)
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
Your sisters daygter is your neice!
A second cousin.
Your second cousin.
4 daughters, 3 sons.
The relationship to you would be your cousin !
Elvis, you "Cannot William Shatner impersonater." your great niece.
Your daughter and your sister's child are first cousins. Your daughter and your sister's grandchild are first cousins, once removed.
Most likely they would not be related to you
They are second cousins