Subtitle: .srt to .sup (blu ray format)

Hello everyone

I would like to know if it's possible to convert .srt subtile to .sub without to much trouble, my main goals is to add it to a .mkv file and be able to select the position of some lines during the movie, ( top of the screen )

I learned how to use SubtitleEdit but as far as I know I'm not able to do so.

Thanks

Kalemvar1