Play 2 media files synchronously with one set of controls for both

Question

I have 2 media files:

• Video+(2x)audio (Movie).
• Audio (Commentary).

Commentary audio track starts with an offset before the movie starts.*

I need to be able to(simultaneously):

• See the video track of the first file.
• Hear one of the the audio tracks of the first file.
• Hear the audio tracks of the second file.
• Play/Pause, FFW/RWD (or seek on the progress bar) all of the video/audio tracks simultaneously.
• Set volume balance between the two playing audio tracks.
• *Set an offset for the auxiliary audio track (commentary).

I need not to mux/resample or in any way edit the source media files as this would disable dynamic volume balance control (and possibly deteriorate quality).

How can I achieve this?

Already tried to no avail:

• Multiple instances of players with global keys. VLC and MPC-HC tested.
  Resulted in one of the instances possessively claiming the shortcut.
• Bino.
  Just doesn't seem to work at all.