Who am I in "Bo Er"

I am Bo Er's nephew and niece; In the Spring and Autumn Period, my nephew was called my nephew's daughter, that is, my concubine's daughter. A woman called her brother's son a nephew. The nephew is symmetrical and has nothing to do with the brother's son. This also means my nephew (this is my nephew). Based on the above, in order to show the difference, if the meaning of nephew is old, it is intended to be "nephew with old meaning".