DVD Architect has something like that. It has a feature where you can make playlists for titles previously imported, but it plays it as one constant title (like if there were three 20 minute titles, it would show up as a single 1 hour title) instead of several played one after the other (though DVD mode on there can't).

So if you wanted to, you could just cut the crawls (as long as it has the same amount of audio/subtitle tracks) and make them seperate from the main film and make two seperate playlists for a '77 and '81 version.

Though as I mentioned before, the program can't simply just take pre-encoded material and use it, which I had to use another program for finalising, and it has a limit of 8 audio and 32 subtitle tracks, so it's not ideal if you want everything.

DVD-Lab Pro has a feature for branching too, though sadly they haven't made a Blu-ray equilivant yet.