Harmy said:
If someone could please find or put together a tutorial on how to replace an audio file with MKV merge, I'd really appreciate it, I really need to study right now.
Here's how to replace asynchronous audio tracks or to add further audio tracks.
First of all, download the fixed audio tracks.
Get MKVToolnix from http://www.heise.de/download/mkvtoolnix.html and install it. Open it and add the MKV-file and the fixed audio tracks.
All tracks including the fixed audio tracks are now listed in the box below. Uncheck the asynchronous audio tracks and check the fixed audio tracks. Choose a new order by using the up and down buttons.
Left click on a fixed audio track, choose "General track options", name the track (f. e. the German track should be called "2.0 @ 384Kbps"), determine it's language and deactivate "Default track flag".
If you want to add further audio tracks that aren't synchronized to the video track yet, you may have to choose "Format specific options" as well and set a positive or negative delay. It's not advised to stretch the audio track during the muxing because this stretching isn't permanent, has to be generated each time while the movie is playing and will stress your system resources.
Click on "Start muxing".