i'll wait for other folks to answer this. if nobody chime in, then i'll. it's a bit lengthly. IS folks? helloooooo...... budd, where are you, bud?
Okay, Tom's question dealt with the four-legged donkey. I tend to look more generally as when two people touch, they form one unit, a single animal with four legs. Both people potentially provide feedback into the single unit. But the person that has better conditioned themselves to be able to manage the combination of ground pushing up and gravity pulling down (as a discrete skill) can add the other person's management of up/down forces into their own matrix . . and thus be the controlling end of the donkey