Hello Tim, first import all the skins into one project. Then fix the draw order for the baseline skin. Once this is done switch skin, and for each piece that has a wrong draw order, create a new slot and skin placeholder in it, and move the item there until this skin is correct and same for the previous one.
Then move on to the next skin: check if the pieces that don't work in one slot may work in one of the new slots you made, otherwise add yet another slot. Repeat for each skin.