Mielr said:
I love ROTJ, and the fact that their relationship was likely manufactured at the 11th hour doesn't bother me one bit. For whatever reason it was done, I have no more problem with Luke and Leia being siblings in ROTJ as I did with Vader being Luke's father in ESB.
But if you think about it, it was actually ROTJ that cemented Vader as a Skywalker not ESB.