because he is secretly an Edo tensei. xdi kinda see it sai is really pale so its hard to tell
not reall y the look the act lik when they do itachis flashbacks he always has that fake looking smile and yeahi dont think so, with itachi's scar and sai's pale face..u cant really tell
there face structures are different too
how could they be they sai dosnt have the sharingan but i no wat u meanmaybe they are distant relatives.