It’s not a bad idea, Anakin Starkiller. It would take heavy editing of the dialogue, possibly to the point of redubbing from OTHER Lee films, but it’s potentially feasible. The thing about editing in OTHER movies is that it has to flow somehow, otherwise it breaks suspension of viewer’s belief. So in other words, it can’t cut from Han talking in 1977 Falcon to 2001 LOTR camerawork.
I think the best possible way to do something like this is to make it really really really small clips, like Clone Wars Cartoon style vignettes, barely 5 minutes at most. Tell tiny little stories that fans COULD imagine were part of a larger narrative. Edit other small snippets of other movies into plausible SW scenarios.