In Unreal Engine, animation blending and mixing are typically handled through the use of animation blueprints and blend nodes. However, the behavior you're describing suggests that the additional animation is not being applied correctly due to the order of operations in your setup. In Spine, when using multiple tracks, the animations on higher tracks will overwrite the animations on lower tracks if they key the same properties. This means that if your additional animation is on a higher track and it doesn't key the properties you expect, it won't have any visible effect. Conversely, if it's on a lower track, the major animation on a higher track will overwrite it.
To achieve the desired effect, you need to ensure that the additional animation is applied in a way that it only affects the specific bones you want to modify, without being overwritten by the major animation. In Unreal, you might need to use blend nodes to control how these animations are combined, ensuring that the additional animation is applied after the major animation, but only to the specific bones you want to affect.
