In this example the skirt has no additional bodyparts in the lower region. In the short skirt (also from bobbie25), the thighs and the hip rotated/twisted around a different axis and the mesh will break

But I think you are touching a general problem which we have when converting clothing, figures and hair to Poser. Most of the "old" problems which used the be solved with morphs and JCMs are not present anymore because DS4 corrects them when they occur. Poser does not have that capability, so the converted items will have problems in certain poses. Pokethrough is easily corrected, but stretching like this and a breaking mesh is not.

Cliff - if you are willing to have a look at it (anime school uniform by bobbie25 and sarsa), I can get a gift certificate to you. It is currently on sale and with PC discount it is 7$. Let me know.