Easiest way to blend an animation with default animations?

I’m working on a game and I have an animation that plays when the player presses a key. The animation moves the character’s upper torso and head, and I’m trying to blend it with Roblox’s default animations, so that these parts’ movement is still partly affected by them. (it mostly looks weird when my animation overrides the torso movement of running animation)

I tried to set my animation to “Core” priority (same as the default ones) and then adjust the weight (with this) in the hope that it would blend with the default animations. Initially it seems to work fine, but as soon as another animation starts, it seems to override mine.

This override doesn’t happen when AnimationWeightedBlendFix is enabled, but I was wondering which alternatives are there (if any) that don’t involve this or replacing the default Animate script. The former seems quite buggy for now, while the latter seems a bit overkill.

I have attached a file which contains an example of what I’m trying to do. Press the “Start animation” button to play it in your character. Animation code is on the Gui.

animationblendtest.rbxl (32.4 KB)