I'm confused about how upper and lower body animations work. I've gone through most of the anims in Ultimate Unwrap 3D and looked at the bones, but I've had no success in understanding how the upper and lower body animations work.

The way it looks, is that the walking and crouching animations (basically all of the lower body anims) all come with an upper body animation attached. BUT, whenever I find an anim that is the upper body alone, I ASSUME that it automatically overwrites the upper body on the full body animation. Am I right here, or am I completely wrong?

So if I were to make an animation with the FULL skeleton (Let's say I overwrite the default rifle running animation), it would show up like that in game. Including the Lower Body.

Also, If I put the extension _upper or _lower will it overwrite them that way?

PS: I'm also assuming everything pelvis down will be _lower and everything above the pelvis is _upper?

Look at this doc from Psych0 Fred's site

Animation System