Mux .sup (standard definition) into MKV file too. Impossible?

[sdk83]

Hello.

I have some .ts files recorded on a Humax PVR 9200 which I would like to edit and process into mkv files. I have edited and demuxed them using Project X so that I am left with 4 files

video: .m2v
Audio: .mp2
Subtitle: .sup with .IFO

The problem I am having is muxing the subtitles into the mkv file. The GUI for MKV Merge will not accept the .sup format. Can anyone offer me a different method such as an alternative to MKV Merge? How about if I used the CLI directly? (I have no real knowledge of how to do this but would be interested in learning). Or is the answer that MKV simply doesn't support .sup? I thought it was supposed to wrap anything?

I have had some success in converting the subtitles to IDX/sub but they don't look as good as the originals in VLC and I cannot get the colour info to import anyway. I wouldn't mind maintaining the .ts format but If I tell Project X to output another .ts file rather than demux it rips out the subs? Also all my .ts files seem to contain an extra silent .mp2 track and I like the idea of being able to tidy up the file.

Thanks in advance for any advice...

[sdk83]

moved here... https://forum.videohelp.com/topic359007.html#1904359

Please delete this thread if necessary

Thanks