how to play .thd(sound) and .mkv(video) , at the same player?

now i got three file
ABC.mkv HD video file
ABC.thd 6CH 5.1 turehd sound file
ABC.flac 2CH 2.0 hd sound file

As i player the ABC.mkv file , it loaded ABC.flac be the sound and i can choose to use it or not.
Video: HVC1 1920x1080 23.976fps [V: Main movie format is x265 [jpn] (hevc main, yuv420p, 1920x1080) [default]]
Audio: FLAC (framed) 48000Hz stereo 2304kbps [A: flac, 48000 Hz, stereo, s24]
Audio: AAC 48000Hz stereo [A: Original Japanese track (AAC 2ch) [jpn] (aac, 48000 Hz, stereo) [default]]
Audio: AAC 48000Hz stereo [A: Commentary track (AAC 2ch) [jpn] (aac, 48000 Hz, stereo)]

And the ABC.thd didn't loaded in the player sound list . It didn't work like .flac or other sound file.
Video: HVC1 1920x1080 23.976fps [V: Main movie format is x265 [jpn] (hevc main, yuv420p, 1920x1080) [default]]
Audio: AAC 48000Hz stereo [A: Original Japanese track (AAC 2ch) [jpn] (aac, 48000 Hz, stereo) [default]]
Audio: AAC 48000Hz stereo [A: Commentary track (AAC 2ch) [jpn] (aac, 48000 Hz, stereo)]

But if i only open the ABC.thd with the player . It can run and it can show the .tdh file be 6CH 5.1 tureHD 48000 .
Audio: TrueHD 48000Hz 6ch 6912kbps [A: truehd, 48000 Hz, 5.1, s24]

That prove KLCP can open .thd , but can't open it with .mkv.

So how could i watch .mkv with .thd file?

Try to use File, Open (CTRL-O), load the .thd file as the dub file, and load the .mkv in the Open field

DONE Thank You

but KLCP still have to add .thd in the dub Audio file list

I only can find .thd in All file , not in the Audio file( all types )

Seems like MPC recognize the format but not the extension

Options > Player > Formats > add .thd to "Other audio"