You can have seamless branching in MKV. I’m not sure how but it can be done - I once experimentally downloaded a couple of episodes of ST TOS and they were MKVs where you could choose which version to watch and it played perfectly smoothly in MPC HC and I’m pretty sure it wasn’t that the whole video was muxed in twice.
Cool. I think I’ve seen people mention it before so that does sound right.
In this case, I’m just going to mux the standard version with your SW crawl just to make sure compatibility is high and no one has any problems. If people want an ANH version, we will see. But Darth Lucas will be doing a version with your 1981 crawl, Harmy, so there might not even be any need.