I’m sorry, I’ve done a poor job explaining. The source has split the movie, intro, and credits into 3 video files, and i’d like to make them one file, before or during the re-encoding process, so that the final movie includes the intro and credits. I’m currently grabbing MKVtoolnix, to see if it can do it, but I completely missed @roawre comment, so thank you for re-iterating, thanks to roawre for the original comment, and thanks to everyone for their responses, getting into this seems overwhelming and i’m so grateful to have your assistance!
Also, the files I have are “.m2ts”, will mkvtoolnix support this, or will I need to encode first? MKVtoolnixs website seems to imply it only really likes .MKV files