I didn't even know public schools allowed children who aren't potty trained. Why is it such a big for preschools then? I had such a hard time finding a preschool that would take him at 3 not potty trained. Anyway, my daughter exercised her will with potty training too. She would hold her poop in all day and at night would have accidents while sleeping (because she couldn't hold it while sleeping). She wore pull ups to bed. The pedi told me to have her clean herself up at night. Which was hard to do at 2 AM but I would stand her in the tub give her the garbage can and a pack of wipes. It took a while but I was finally able to get her to go potty before bed. She's almost 10 and I still have to tell her to go poop before bed if she hasn't yet that day! Your foster care training was so true, the pedi said the same thing to us.