The wool of a WIO is basically just a wool cover, the snap in contour makes it a WIO. You wouldn't wash both pieces together, the contour would get thrown in with the dipes, the wool would be handwashed and lanolized seperately like normal. I wouldn't make a true WIO with the dipe sewn to the wool, the wool can be reused for a week or more (depending on how many are in rotation) and the dipe itself can only be used once.
