TLDR: I'm trying to create a lossless, single file rip of the Theatrical Cut of Alien from the 4K UHD but with one scene/segment from the Director's Cut in place of the Theatrical Cut's version - basically, I want to mix and match segments from the two playlists into one file, but I'm having no end of difficulty.

Details:

I'm in the process of ripping all my 4K UHDs to a hdd so I don't have to hear the noise of the disc spinning during playback. All was well until I got to my Alien UHD and saw that, rather than one m2ts file, Alien cones on about 50 small m2ts files. After a while I realized the reason is because Alien UHD contains both the Director's Cut and Theatrical Cut, and breaking them into chunks is a (rather clever) way of saving disc space.

I then started looking into merging m2ts files losslessly, but here's the thing: I had a little idea. See, I don't care for the Director's Cut mostly, I think the Theatrical Cut is superior in every way...except one. I love the DC version of the scene where Dallas and Ash are operating on Kane. In the DC version, Lambert slaps Ripley and, personally, I've always found this hilarious.

It's always been the one annoying thing about watching the Theatrical version and I've always wished it was possible to swap just that one scene for the Director's Cut version, losslessly...

Well, if the movie comes in chunks, and it's possible to merge the chunks, I should theoretically be able to "mix and match" scenes from each version, no?

I know exactly which segments need swapping, too: the Theatrical version is segments 702 to 732 on the disc, and 711 is the scene in question. The Director's Cut version of the scene is segment 691. So, in theory, I should just be able to swap those segments around, so the order goes 709, 710, 691, 712 etc.

Only thing is, no matter what I try, nothing works. Finding software that can do lossless merge of m2ts files is hard enough - many like HD Video Factory claim to be able to but they actually re-encode the video, and the resulting file had no audio for some reason - but even when I find one that supposedly can, it won't let me mix and match. And when it _does_ let me mix and match, the resulting file is corrupted in some way.

I did manage to use txmuxer and it did appear to work, but the resulting video's audio was out of sync and the frame rate appears choppy.

So, can anyone help me with this or point me in the right direction? I sure would appreciate it.