Newbie question for adding subtittle to ripped MKV

[yd8552]

Dear all,
I got some mkv files. they were ripped by someone and the whole package comes with the subs and a file so called "mkv2blueray". after running the mkv2blueray file, it basically load up tsmuxer and then use imageburn to create either a DVD-5 (for most of the 720p) and DVD-9 (for 1080p). it has the option to choose which sub to want to add into. the whole package came with some .SUP files (usually 8-9MB each), I did choose eng.sup and the finalized DVD5 played fine on PS3 or Panasonic BP60. I would say they did pretty good job, easy and simple to use and the quality of the movies were awesome.
Here is my question, how can I make the sub as I wish (say adding Fin sub).
1. If I find the sub in the langurage I want in other format, like SRT, do I have to convert it to SUP file first? which software can do this job? SUPread, sub workshop?
2. Once I create the SUP file, do I have to save it in the same folder as other sup files came with the whole package to be able to choose when running "mkv2blueray" file?
3. from what I tried, first I found one SRT file, change the name to the same as the movie, save it into the same folder as other subs as SUP file. But the finalized D5 and D9 can have all other original subs but not the one I created...
Can you help with it? since it is critcal for me to add sub into those BD ripped moives for my parents...
Thanks a lot

[Baldrick]

Use easySUP to make blu-ray sup files from srt, http://forum.doom9.org/showthread.php?t=149160

But downloaded bd ripped movies? Just wait for a blu-ray release with correct subtitles or rip from your ORIGINAL blu-ray and then try use multiavchd to add subtitles.

[yd8552]

Thanks Baldrick. I know those BD ripped movies are not the best.. but I don't have BD drive that can rip BD and also getting those BD remux takes too long..
Thanks, I will try easysup.