I’m not sure if this works with the SUP subtitles, but for the SRT, just rename them to the same name as your video file but with .srt instead of .mkv and put them in the same folder - this way it will work on most devices - like both my BD players and my TV can show subtitles that are muxed in but my parent’s BD player and TV can only show subtitles if they are added the way I described above.

Also, someone put the workprint on myspleen, which I’m completely fine with, though it would have been better to check with me first.