Neither Nor & Either Or
E.g.
I haven't met my mother or my father (more common)-
I have met neither my mother nor my father (more formal)- No he conocido ni a mi madre ni a mi padre
Neither my dad nor my mum smokes- Ni mi madre ni mi padre fuman
My dad doesn't smoke and my mum doesn't either-
My dad doesn't smoke, neither/nor does my mum- Mi padre no fuma, y mi madre tampoco
Either my mum or my dad has to attend the meeting- O mi madre o mi padre tienen que asistir a la reunión