DS, 2.5, fantastic at peeing in potty, [though still haven't got our hands on a travel potty when out, anyone know where to get one?] But he always asks for a nappy to have a poo. No accidents, he always asks, but how to persuade him to poo in the potty? He just won't. He doesn't sit down to pee either, he stands and i catch it. Any advice for clueless here?