Muxing multiple video+audio streams in MKV container?

[HelmedHorror]

Is it possible, perhaps with MKVToolNix or something, to combine multiple video and audio streams into a single MKV file for convenience? When I use MKVToolNix to try and do this it just ends up crashing any video player that tries to play the non-default video stream as soon as it ends, perhaps because the timecodes are different.

[kuchikirukia]

Doesn't crash MPC-HC.

[HelmedHorror]

Doesn't crash MPC-HC.

I use HPC-HC too; that's the one that crashes on me.

It crashes as soon as I touch any of the controls (seek, pause, etc.) after any video stream runs beyond its length.

For example, if video track A is 17:32 long, and video track B is 4:51 long, MPC-HC crashes if I touch anything after 4:51 while playing track B. If only MPC-HC would change its seekbar timeline to match the video track that's playing rather than keep the same timeline of the 1st video track.