Combine multiple animation transforms in one animation

I'm currently doing animations for my characters in a game I'm making, and I need to redo some of the animations, in a small way. The problem I have is that I have the Hips rotation, and the Spine rotation, but I want to merge all of those rotations onto the Spine rotation part in the animation tab. I have tried copying over all the key-frames from the Hips rotation, but that just overwrites everything, not adds to. Is there an easy way to do this instead of adding them all manually? Because I need to do it for over 13 animations (and probably more in the future). Many thanks