The problem with bullet physics is that it works best with flat planes or enclosed objects. So you can make a flag or cape and you are good. You can also make a Jello cube that wiggles or a Santa Belly that jiggle. But you can not put a pair of legs inside a skirt, because Bullet will make a proxy object to calculate from and for a skirt it will look something like a bell, with the bottom closed. Years ago someone on the old RDNA forums asked about dropping balls into a bowl and that they were falling off the sides without going into the concave part of the bowl. That was because the opening was being closed by an invisible topping. To get around this I told him to put a bunch of flat planes inside the bowl make them invisible and drop the balls onto those planes. It mostly works if you make the planes small enough . The problem you run into with the skirt is that as soon as you make the legs a collision target and they are inside the skirt then bullet tries to avoid the collision and starts the skirt moving until it is going fast enough to fly off the body. I know I have tried it.

So there are two ways around this. One make the bullet physics move a bunch of weights tied to a skirts body handles. Two make objects that move and have the clothroom handle dynamics of the skirt colliding with the objects.

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13