I have not encountered a center-pivot, folding disc, although I know some were made. My guess is piggy-back feature included too much product liability during the process of lifting/folding heavy rear gang over the front gang and the reverse, unfolding. Major injury probability in the design; too easy to amputate a hand, an arm or a foot.
While undoubtedly there was weight transfer when folded, I do not know how much more weight transferred relative to when Top Link is shortened to lift, or near lift, rear gang above the ground.
When the rear gang is actually OFF the ground as result of a shortened Top Link, rear gang weight puts major stress on the Top Link, especially when bouncing across rough land. When folded, a piggy-back disc would not overly stress the Top Link.
Ferguson's Three Point Hitch design transfers much implement weight to the tractor's rear tires and to a lesser extent, front tires.
I believe our Honolulu OP needs a Bush Hog adjusted for scalp cut and Roundup. Big tractor: Kubota 9540DT