I figured it out, and you're not gonna believe this. It seems me and you totally skipped over one crucial step. There's an additional material slot required on the Novabeast body. That's it. Just set it to whatever your base body material is, and you're good to go. I can't believe I didn't understand that from the above thread.

Looking into blender, it seems that the breasts work properly, but upon exporting to Unity, it breaks entirely, and the shapekey adjustment doesn't change.

Fr, it is awesome nonetheless (I also noticed that there are some holes on the side of the body but like- I'm not naked enough to actually care.)

That's the struggle I'm dealing with, yeah. It seems that when these assets were made, they were tailored specifically for a flat chested body, and the actual breast mesh no longer exists on the avatar for it to be made. I'll take a look at the animation clips to see what I can't find.

@NothingIsAnyway So, in this case. It is shrinking the actual chest mesh, and increasing the scale/position of the nip assets

I think i see why the breast blendshapes don't work. Instead of merging the nipples to the bone of the breast, the nipples are instead taking the place of the breast blendshapes.

@aria768 Holy shit, that worked! You are a lifesaver. The only problem I have now is the fact that the breast blendshapes don't work at all, they just sink in the chest, and move the nips around.

So, I did exactly as instructed using this thread.. and I ran into some sort of problem. I've gotten the overwrite to work properly, meta intact. Things look good.. but when hitting play, using gesture manager, or anything like that- The avatar crumples into a ball. Happens every time I try to adjust the FBX in general, and I cannot for the life of me figure this out.