A.P.
Our son was pee potty trained for at least 6months before he started going poop on the toilet. For whatever reason he just wouldn't go in the toilet. Because he pees excessively at nap and bedtime he still wears a diaper/pull-up for those and that's when he'd go poop. Then one day, my husband took him into OUR bathroom and told him to go there and he did. And he's been using the toilet ever since. He still have an occasional poop in his diaper after nap or in the morning, but it's very rare. Best wishes!! It can be very frustrating and tiresome, but it does pass. You just have to find what works for him.