How to hardcode 3d sup subtitle to 3d sbs (side by side) mkv video

mkvmerge GUI

My audio field is empty after loading the *.mkv file.
Does anyone know how can I fix it?

I can not add sup file.

so I have to wait 2 to 3 hours to add a fucking sub to a movie? nice method fucking idiot dislike

Next time run your bath before or after when making a video!

thanks! the easiest way I have been watched.

Thanks for that..