It is not entirely a quirk, is more like the technical way of linking parts in Poser. A given group of a figure can only be in touch with two connecting parts at a time, the preciding and the next, so the lShoulder in this figure (very nice BTW) is in touch with more than one (actually like four) That's why it is breaking in the neck and the rShoulder which are the two extra groups. Hope this helps