Originally Posted by jet150
I'm pretty sure you add the idx file. It's whatever files that shows up as one of the possibilities when adding a track to the mkv, in mkvmerge. Once you add the subtitle track, you have to tell mkvmerge that you want it forced, else they won't pop up automatically. I don't remember how to do this but I think it involves right-clicking on the subtitle, in mkvmerge, and doing something from there. Either that, or it's one of the options on the first tab of mkvmerge. Either way, telling mkvmerge that that subtitle track should be played all the time is in there somewhere. That's how I do it. Also, when I run it through bdsup2sub, I only save the forced subs.