I was just speaking about the idea of somehow seeing Vader learn of Luke in AnH. Alas that is pretty much a fan fantasy which ILM will never actually put together as an extra scene for AnH.

One potential (much easier) idea I had to substitute for such an idea is to modify the scene in the DS trench run when Vader says "the Force is strong in this one". Perhaps more can be made to really highlight that scene? Maybe a dramatic pause in the dialogue..."The force......is....strong in this one" or maybe even some new subtle dialogue addition? Perhaps just linger a bit longer on Vader as if he's feeling a tremor in the force or something unusual as we cut back to Luke's ship in flight.

Maybe even directly link that up as a distraction which allows Han to get the drop on him?

Unfortunately there's no way I could put this together on my crappy PC...but maybe someone else could as a test?

Anyway just an idea.