Is there a way to tell the animator what to do?

I’ve reinvented the wheel like 20 times.
Roblox blending back in 2018 before 19, lets say, a arm motor has a keyframe at frame 2, and not another one until frame 6
what roblox did back then was see that between each keyframe each step that frame i, frame i + 1 or last and next do not have a keyframe for said motor6d, then it fell back onto a lower priority if there was one, if not then it fell the motor back onto cframe.identity (zero)

I’m wondering if its still possible to do this behaviour with modern animator because reinventing the wheel is both incredibly unoptimised (despite mine working) I just want a easier method.
I’m planning on using this to recreate unintentional glitches which the only way I can do this I’ve found is by completely removing the track of the motor6d from the higher priority animation

If this is the wrong topic please feel free to tell me, I’ve added some tags.