This is some kind of personal thing, and it will affect the story IN A HUGE WAY... It mainly affects ROTJ, but there is one little scene here.
Dont make Luke and Leia Brother and Sister... It just feels forced and stupid. It makes no sense that nobody ever felt the force in her, why obi-wan never even cared about her rescue on A New Hope, why nor yoda nor obi-wan even cared training her AT THE SAME TIME as Luke. And it breaks that tension between Han-Leia-Luke, without really giving anything to the story.
It wouldnt be that hard to edit from ROTJ, the biggest change would be how to make luke get angry with vader... But any other time is just cutting dialogue.
In ESB youll have to cut down the "No, there is another" (thats why im posting this here first and not waiting untill ROTJ:R)
i find it dumb, there have always been hints of them being related in episode 5. in my opinion the way i see it with those being against luke and leia being related is because of their little kiss which i have no problem with considering the context of what was happening in that scene