anyone have any advice on pottytraining? my stepson will be 4 next month and still poops in his underwear. he does it here and at our house. he holds it in so long that it comes out tennisball size. we've gotten him to poop successfully once. but we are constantly having to throw out underwear (we're not allowed to wash anything with poop on it in the laundry room here). we've tried rewards, we've tried punishment, every possible thing we could think of...

I feel like 4 years old is too old to be pooping his pants.