Monroville:

Then again, why didn't Vader know that Luke was his son in ANH, being that someone would have told him that the droids were owned by an Owen Skywalker, father of Luke Skywalker.

Am I misunderstanding your context, or are you saying Owen's name was Skywalker? And even if it were, why would Vader assume Owen had a son, and that that son was the son Vader didn't even know he had?

Hm.

One can always take Alec Guinness scenes from ANH and transparentize him, if that's possible. Whenever he speaks, never show his face.

That's ridiculous. Any editor who would do that needs his hard drive erasing.