So, I've tried a lot of things without much luck; now, I'm wondering if it's even possible... what I'm trying to do is use meshes, sound, textures, etc. from a BSA I have packaged to replace those of the official Oblivion BSA resource files without editing them. Pretty much just like any other invalidation but with all the files in a BSA. I want to be able to replace the official data files, but at the same time, allow other mods to invalidate my files through their unarchived files. Is this even possible? If so, how would I go about it?

I'm guessing this isn't possible? X_x

I'm not entirely sure I follow what you mean, however:

If the file has exactly the same path and name as the original file that's in the "Oblivion - XXX.bsa", and if your BSA is dated after the original BSA, then your file will take precedence and replace the original file. Any loose file in your DATA folder that has a later date than your BSA will replace the file from your BSA.

This requires that Oblivion knows to load your BSA, which means it has to be listed in the "sarchivelist" in the Oblivion.ini, or has to share the first part of its name with an active ESP file.

ie: your bsa is named "MyMod.bsa" or "MyMod - Graphics.bsa", you'll need an esp named "MyMod.esp"

Yes that is exactly what I'm trying to do, thank you. All paths and names are the same in my BSA as the official's. However, I have tried changing the dates on the contents of the BSA and the BSA itself; either newer or older than the official BSA, my files still don't take precedence. I have tried putting my BSA at both the beginning and the end of sArchiveList for each attempt, but nothing seems to work. "bInvalidateOlderFiles" is also set to "1" by Oblivion default, so in theory this should be working, but it is not... I haven't even begun testing if files in the Data folder will invalidate my files yet (in fact, the data folder is exactly as it should be for a fresh install, without any textures or meshes folders), as it wouldn't even matter if I can't get this step to work. =/

I just want to invalidate the vanilla files with my own, while leaving my files open to invalidation. I am open to any method of doing this. ^^;