What is the proper way to blend/replace animations for half of the body?

I am currently working on a 2.5D side scroller game where my character can run/jump/fly while always having his rifle/pistol directly aimed down ironsights. My blendspace works correctly during my idle position, but when I jump or start moving, the animation changes (blendspace aiming still works) Any ideas on how to get the top half of the body to always keep the same pose, while the bottom half runs and jumps? I will post video/screenshots if requested.

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