Ah, yes, that was a nice one, I'll keep that.
Thank you Luc very much for these hints, its been incredibly useful. I now also understand the mechanisms better, which is a prerequisite to know how to do it simple (it is often due to my testing of many variants before getting to work that my test models ends up being a bit über complex... ). But I think I have improved now.
BTW, the reason why I separate the bongo curves and points (a kind of a "exoskeleton" or "stick figure") from the contours and surfaces is that I can copy that bongo "stick figure" over to my final 3D model and then just re-enter the Bongo defs to make the 3D model live (the contours where copied from the 3D model in the first place, so the structure of joints is exact).