Mixing two animations with bone filters for upper / lower body of armature

Godot Version

4.4.1 stable

Question

Hi, I am using an animation tree with tree root blend tree.
The current setup is a blend2 to switch between an idle and a running animation. The output of this goes into a OneShot where the shot is connected to an attack animation. The filters of the OneShoot are set to only affect everything from the bottom spine bone up, while both legs remain unaffected, so the attack animation is played either in idle or in run.
In principle this works, however the issue is that in the attack animation the lowest spine bone (which is the parent of all bones) rotates first to the right (charge up) then to the left (stab) and for some reason the legs follow that rotation. Is there a way to un-parent the legs from the spine? Or any other way so that keep the rotations / positions from the run animation?
The animations were made in blender, but I did keyframe the deforming legbones as well as the IK poles & targets, so thier positions should be saved in the animation, right?

Here you should be able to see the legs pointing forwards while the char is running and as soon as i fire the attack animation they rotate with the spine bone:

Or is my approach to this completely wrong? How do pros handle playing different animations on different groups of bones?

Or do I just have to leave the first spine bone’s rotation and handle torso rotation with the rest of the spine bones? I wouldn’t like that because rotating it makes kind of a hip rotation for the legs with the IK setup in blender

Hi, I have exactly the same question right here: How to make animation blending work?

I’m wondering if you ever figured out what to do?