mkvmerge as "transcode" engine (for native subs on Bravia)

[Fiddl3]

Bravia Smart TVs doesn't suport external subtitle files via DLNA, but internal subs (in mkv contrainer) works fine.

mkvmerge can mux video+audio and external subtitle file to MKV contrainter in few seconds.
Is it possible to use mkvmerge to mux video files with external subtitles into mkv in PMS ??

PS.
Sorry for my poor English