Sorry, I thought you meant the milbrats. The problem you might be having with standard poses on the ordinary p4 kids might be because of their actual size. The hip location is generally going to be different than with the larger p4 characters. Essentially though they use the same joint set up as the other characters but some of the zones differ. You should be able to apply a set pose and then just tweak it accordingly and turn IK off to reposition the hip so they're closer to the ground. There are a few pose sets for the P4 kids available around the net free, such as basic sports and suchlike. If you don't have them it might be worth poking around the freestuff areas and checking out Lannie's links list at 3dmodelworld