Quote
"The man Leia called Father was obviously not her father. He is part of the group that ends up having to fight Darth Vader in the film that will be out in 2003 [laughs]. The part that I never really developed is the death of Luke and Leia's mother. I had a backstory for her in earlier drafts but it basically didn't survive. When I got to Jedi, I wanted one of the kids to have some kind of memory of her because she will be a key figure in the new episodes I'm writing. But I really debated on whether or not Leia should remember her." - George Lucas: The Annotated Screenplays
Of course, this won't prevent some people from choosing to believe otherwise, but doing so completely sucks all the emotion out of that scene, but what can you do?