Need help animating separated Bones / Bake workflow

Hi. I created and animate 10 different animations for my skeleton.
The model have various bone, Inverse Kinematics bones and all work ok to do the task.


The last animation i need is the death of skeleton separating all bones in the ground.

This model will be exported for game engines, so all animations need be in one FBX file.
I created the last animation removing the parent bone from all bones, so i can move the bones freely.

But after this the other previous animations are destroyed, the bones move in wrong way.
I tryed bake these animations thinking this will freeze the parts in the right way. But after deleting the parents bones the baked animations change in wrong positions.

I separated the NLA layers so anybody interfere in the animation. But the errors are the same.

I would know if anybody know the right workflow to create this death animations.

Thanks.