Let me give a very crude and incomplete *illustration* (nothing more than that and not all that accurate except as an illustration) of pulling silk and reeling silk: Have someone grab 2 or 3 fingers of your extended right arm and right hand in their fist and hold them firmly so that you can pull back with your body (not your arm or hand). Pretend your arm and hand are nothing more than a towel or piece of cloth and move your torso backward slowly until you can feel the stretch in your fingers, hand, arm, shoulder, and across your back. Your partner holding your fingers is now connected to your middle via a slight tensile stretch. No connection, no way to control the fingers with your middle except with normal muscle, right? So somebody who "doesn't use that extension of the body" for dantien control is blowing smoke. OK, so that's a crude example of "pulling silk" or "chousi jin".
Yes, it is, but you know what? That description EXACTLY covers the way a CHILD pulls against force. A CHILD uses "pulling silk" or "chousi jin" in his movement....
And the child will naturally add body twisting and turning to that energy, connected through the center to the ground.
What you describe above is exactly what I described in my Aikido Journal online blog about toddler movement. I took my daughter's outstretched hand, she pulled back and sank her weight as she stepped back. She had a direct line connection, extending my arm and connecting to my center.
So thank you for reinforcing my information on that subject.