Hov to attach 3D-subs (SBS) to existing 3D-MKV file?

[noones]

Hello,
I have searched through forum and didn’t find any answer to my problem. I have several films in 3D MKV (SBS – 1920:1080) files. But they were without subs.
Ok, I have got 2D SRT files and converted them into different 3D formatted files (SUB/IDX and ASS/SRT).
Then I did mux them into the MKV file with “mkvmerge GUI” tool and everything works just great on PC (Win7 and VLC mediaplayer), but my Sony BDV-EF200 does not show the subtitles. I can select them, but nothing is shown.
So I decided, to hardcode them into the film. Ouch, here I am now in dead end. I tried at least 10 tools for MKV conversion, but till now no luck. DVDfab is most useful tool tested until now, but I still cannot do the exact job. So mission is to hardcode 3D subs in 3D MKV existing video, and not to lose quality (Full HD, Half SBS).

Does anybody have a solution?
Can this be done by DVDfab or not?
Is there any other option?

Thanks in advance!

[noones]

OK, little correction for "I can select them, but nothing is shown." it's not true - I can select them and subtitles are shown, but only in the center of picture - like 2D subs.