I find this still from one of the animations quite fascinating, there is also a still of a loading buoy(lower picture) on another video, same principle.
I believe there is a Bend Stiffener Latch (BSL) on the bottom of the center shaft,(recently we saw 2 in the shop), somewhere towards the top there should be an annular flow port, (recently we saw 2 possibles) the whole center shaft could look something like we see here. #msg-34659727
Does the top then get an attached "bell" (2 in the shop today) or are the "bells" male ends for the Latches?