Un huh. lIke Phil and EnglishBob said -- welcome to the Poser Skirt Problem. One thing many people do is omit buttocks. That can at least get you into a knee-length skirt that works. There have been some limited successes in welding siblings (which Poser does not normally allow you to do.) To my mind the best methods work on a "flubber" principle, where the skirt is one large group and poses are applied to it as a group. Morphs (truly the only way to get a decent seating skirt) -- Serge Marck has made good with those. Anton's Reverse Heirachy Affectors. I've been experimenting myself with "Conformal Clothing"; a combination of phantom limbs and body handles controlled by ERC. Or you can just go P5 with it and use dynamic cloth.