Q&A: pooping only in diaper

Jillian writes:

"N (boy) is 3 years old and toilet trained for pee and 'diaper trained'for poo. That is, he can control when he poos, but refuses to do it in the toilet. He holds it until he's in bed for nap or the night (the only time he gets a diaper) and then lets loose. I've tried every form of incentive and they don't work. He's done it a couple of times in the toilet for chocolate, a cupcake AND 'toilet fairy' stickers (yes, all at once!) but he's back to doing it in the diaper. He has a fearful reaction to the idea of sitting on the toilet for poo combined with that 3-year old need for control. I can't even make him do it in the diaper in the bathroom - he has to be in his bedroom. I'm not pushing the issue because I don't want him to get constipated but changing a 3 year old's poopy diaper is getting old fast. Quite frankly, it's gross.

Would love to hear from anyone who's been there, done that."

I have no idea. I wish I did, but as I say every time we have a potty learning question, both my boys trained themselves, and I was just kind of the facilitator (and my babysitter B, too, with the second one). So I really have no secrets or much to offer on this.

So I'm tossing it out to the readers, and hoping someone's been through this and has some words of advice for Jillian. I agree that it seems counterproductive to try to force it. Would it help to have N shadow another kid who poops in the toilet so he'd be encourage by peer pressure? It sounds like rewards aren't working. Anything else anyone can suggest?