How? If you want to implement natural decaying to skeletons, then you need to modify decay frames for all non-siege units. Each unit generally has 400 - 900 decay frames (in 16 angles). This is incredible amount of work.
Maybe generating skeletons linked to blood would be doable, but even then they would need to be generated properly for all 16 angles. And it would not look nearly as natural as AOC/HD decay animations.
I don’t know, because I didn’t edit data file. I guess, that you need to edit frame display times for unit decay animations, so that frames are displayed longer.