musicman - I think it would be better to try to edit Episode III to fit Vader's line than vice versa. I've come up with some possible ways to try it--I think they're in the Starkiller Ranch thread.
Changing Kenobi's one line in ANH from "Your father" to "I" doesn't bother my too much but I do agree with you musicman that it eludes to a larger problem with the overall Star Wars saga. In my opinion the OT is flawless, storywise that is. The plot, the dialog, and the characters were all executed close to perfection. The true problem is that the PT is so heavily flawed storywise that it now makes the OT look like it's full of contradictions and inconsistencies. Lucas royally screwed up when making the PT. The PT is so full of garbage, unfortunately it's impossible to fix all the mistakes with simply cut and paste editing. The story of the PT greatly needs to be rewritten and reshot for it to be faithful to the OT. We know that this can't be done so the easiest thing to make the entire saga make more sense is to edit and change the OT so it fits more with the PT, when in fact it SHOULD be the other way around. I absolutely love what Adywan is doing with ANH so far but I do have fears that eventually the OT is going to be changed from it's original look, feel and story just so it's more faithful to the crap that is the PT and all for the sake of a fluid storyline. I will quietly keep my fingers crossed and pray that this doesn't happen. So far Adywan hasn't done anything for me to believe he doesn't have anything but the best intentions for Star Wars at heart. But I admit I worry for ESB and ROTJ.