I've seen a few people ask how to merge mpq's and I didn't see a guide on it (perhaps cause it's so simple?) so I made one.
Tools Needed:
MyWarCraftStudio
Ladik's MPQ Editor
Make a new folder on your desktop and name it something you will remember.
Go into MyWarCraftStudio and open one of the files you wish to merge.
Extract those folders you want to merge into the folder on your desktop.
Open the another file you wish to merge.
Extract those Files to the same folder on your desktop.
Close MyWarCraftStudio.
Open Ladik's MPQ Editor
Go to Operations ---> Build MPQ from directory.
Select where the files are coming from, where to save the mpq archive, and ignore the last part.
Click create and enjoy your one consolidated MPQ.