Logan is pee trained, but refuses to poop on the potty. He denies having to go poop, but begs to get ready for bed (because it means he gets a diaper on) and then will hide and poop in the diaper. I'm concerned that he's holding his poop all day (or longer) to poop in a diaper and he seems scared of going on the potty (he won't even entertain the idea or try).

Any advice??