Does the new Emperor/Vader scene make sense?

I love the new scene with Ian McDiarmid because he played Palpatine throughout the whole series, and it seems weird to hear Clive Revill when I'm used to hearing Ian's voice as the Emperor. However I'm confused about one thing. When Sidious tells Vader that their new enemy is Luke Skywalker, the son of Anakin. Why does Vader say, 'How is that possible?"

He sound surprised that his son is living and yet on the very first scene of Vader talking to Admiral Piett, he says "The rebels are there, and I'm sure Skywalker is with them"

So, he already KNOWS of his son. Is he just faking the surprise when he talks to Sidious?

Yes.

Yep, and I think the Emperor knew Vader was playing dumb.

Answer: GL sucks. He should leave his Original Trilogy the hell alone.

Originally posted by theredbaron
Answer: GL sucks. He should leave his Original Trilogy the hell alone.

Everyone should get over it. It's his films, he can do what he wants. If people really DIDN'T like what he was doing, they wouldn't continue to put billions in his pockets.

Oh, and Vader was attemping to act innocent. The Emperor knew it, and so kept questions going into ROTJ, about Vader's feelings and loyalty.
It's games within games - Palpatine knows the destiny of every Sith lord is to ultimately kill their master, because the dark side makes them lust for power. That's why he sees Luke as someone who can replace the father; Vader thinks of a time when he and Luke kill the Emperor and rule together. But Palpatine, if it came to it, would be content to do without each and ensure his rule.