I know how to add an .srt file to an mkv, but is there a way to make it so when the mkv or movie is loaded, a specific subtitle automatically loads and plays with it? Basically a forced software subtitle, almost as if it's hardcoded? I don't see any such options in MKVMERGE, am i missing something? It seems to me like there should be an option for this...
I'm not sure if this is what you mean, but if you have an external .srt file with the same name as the .mkv (in the same folder), when you play the video with VLC, the external .srt subs start automatically.