To manually update a mass markings pack and use it, could you just add in all the marking files, and then copy/paste the new marking code into the new .cfg after the main markings?
Like:
[Main markings code, tiger, cheetah, etc. Base game markings, this part of the cfg is untouched]
[Mass Markings NEW markings code only(tabby, badger, etc), pasted into the cfg file after the main markings codes]
i'd assume that'd be how to update it properly without messing up the base game's marking order?