Don't delete the dynamic version of the skirt yet. You may find potential uses for it. Just save it as a last resort.

I don't always find the Poser manual to be helpful. But the chapter on the Cloth Room has a little section on dynamic vs. conforming clothes, part of which reads: "Items such as socks, bikinis, or tights don’t need to be dynamic since in real life these types of clothing tend to be close-fitting with little to no room for independent motion." A pencil skirt isn't quite the same thing as tights- but nevertheless it's close-fitting without much room for independent motion.

Depending on how the conforming skirt is constructed, it could be a challenge to get it to fit right around the crossed legs, then maybe you'd want to reconsider a dynamic simulation. (But in that case, I still wouldn't do a full-fledged simulation- I'd just do one to sort of shrink-wrap the skirt around the crossed legs.)