are you using boned meshes?
Why not export the clothing ie skirt with the bones it uses ie pelvis, rthigh,lthigh and then like said animate them the same. You shouldn't get it popping through then if you rig it correctly.
Why not export the clothing ie skirt with the bones it uses ie pelvis, rthigh,lthigh and then like said animate them the same. You shouldn't get it popping through then if you rig it correctly.