Combining mutliple MKV

[licon7]

Hi all, I'm pretty new to using mkv files.
I have rendered a video in my 3D software and it made a mkv file
If it worked correctly the videos should all have transparency.

Now for my question:
Is there a way to combine those mkv files on to eachother? not side by side, but just like transparent pictures on top of eachother.

[Woodstock]

This is a question for a general video forum, not a forum dedicated to ripping video from DISKS in MKV format.