I've got a mostly academic question. What are you allowed to put under your kid who has stopped using diapers but can't always make it until you stop the car? My general plan is wool pants and not really caring if the seat gets peed on and I know this is strange to most people. But I'm the only person I know in real life who has an already potty trained 2 year old so this is coming up in conversation and I don't want to tell people to use things that are not allowed. Can you put cotton diapers under a clothed kid or between the kid and the crotch buckle? Are those thingys they sell that go under kids allowed (what are they, puddle pads or something)?