3 yo and pooping in diaper still

SO as my first post, I need some help.
I have a 3 yr old boy who has been potty training for what seems like forever. He is currently in underwear all day and pees on the potty with no issues at all. He goes when he needs to, no help reqd, etc.
HOWEVER, when it comes time for his nap he has to wear a diaper because he always poops in it before he goes to sleep.
I literally have him go pee, ask him to go poop too, he starts crying saying "but I cant, I dont want to!!!!". I put him in his bed, and he usually tosses and turns quite a bit before falling asleep. I check on him 1-2 times and whisper "do you need to go poop?" "No.". Not minutes later, over the monitor, I hear the tell-tale 'grunting'. He poops almost immediately after I lay him down.
For a while, I understood, ok, he is just no comfortable with the toilet and pooping yet, it will come. But come on! It has almost been 6 months of this.

WWYD?

I wish I knew...my 2.5 year old daughter is the same! Has no problem peeing on the toilet (although if I don't remind her, she gets lazy and will use her pull-up), but will not poop in the toiler or potty. She poops at unpredictable times, so she has to stay in a pull-up. I have tried going cold turkey and just using underwear, but it didn't help and just resulted in a lot of messy underwear to clean. I even resorted to rewards...which I am basically ethically against for this type of thing...but it didn't work! My two sons potty trained with not much trouble...just did it when they were ready, but this one is a stubborn little thing! I hope some of the other ladies have some advice, I could use it too! I have a feeling it is just a waiting game.

My son was trained for pee before he was 2.5 but he would wait till nap or bedtime when I put a diaper on him to go poop....I was having a heck of a time then it was like a light went off and one day he started going in the toilet. I have heard some don't like to go in the toilet cause it "plops" and either scares them or gets them wet and its easier to get them to go in a potty to avoid that and ive also heard that a potty is more like a squatting position and therefore more natural. at this point hes just being stubborn cause he says "I don't want to" what if you threatened him with a time out ? would that work for him? I had a dcb that knew when he had to go but couldn't be bothered and was 3.5 so I put him in the time out circle and miraculously he remembered to tell me after that every time ....it only took once. when they know they have to go and choose not too then I think you have to give them a deterrant (time out ect) but when they are younger and truly don't know or are just learning then I wouldn't never give a time out but at his age and since its been months maybe you need to step up the expectation.

If you leave the child on the potty will he get so groggy he forgets and loses control and just does it. Have actually done that with a child that was to wear underwear at naptime but I had a no pee wear a diaper rule for her for the same reason. Sometimes it mattered how soon after lunch she was going down so maybe he needs to be up an extra 15 minutes before being put on the potty to sit till it is done.

When an older child has an "accident" that I feel is because they just couldn't be bothered they are sent to stand by the bathroom door till I get there - basically becomes the same as time out as they are told they can't play with a peed/poopy bum and to go stand by the door till I can come and change them and then of course I have to make things ok in the playroom before I can leave it so I make sure child has to stand for a couple of minutes - just enough to get my point across.

If they are in underwear they are also expected to be independent in dressing so they must remove the wet stuff and I wash them down, put on the dry pants since they will be harder to get up then leave them with a pile of clothes to finish. While I go do something fun with the others or get out a game I know they like. The idea is to make their life miserable when they have accidents as an incentive to not do it. There are ways to reward without giving a reward. The reward is for staying dry not going.

Yea exactly. This is him choosing no not use the toilet, and preferring the comfort of the diaper. So he is holding it. I should mention that he has gone poop in the toilet in the past, 2 times at his house, and 2 times here, so its not totally foreign to him.
I can always tell when he really needs to go because right after lunch and he has his diaper on, he literally WAITS by the bedroom door to go to bed (to poop). And will start to cry and whine "Can I go to bed now!?!?!" if I am still tidying and the other kids arent ready to go down yet.
Arggg its soo frustrating LOL!

The thing is, I don't see this as "choosing" like with a child who does it sometimes, but other times is just too busy or lazy and doesn't want to take the time to go to the toilet. It is definitely a comfort thing. My daughter has pooped a tiny bit on the toiet a couple of times too, but I know she is just not comfortable...she can't relax enough to let it come out. I have tried the potty as well with no success. I would really try to avoid making it a power struggle. If he goes to bed in underwear, will he poop in those too (I know my daughter will, but maybe your dcb is further along in the process)? Could you make it really fun to wear underwear to bed? Like some special underwear that he gets to decorate (get his parents to supply them) with markers or fabric paint and become his magic naptime underwear, but he can only wear them if he first poops in the toilet or potty ? Personally, I would not punish him for pooping in his diaper as I wouldn't want to attach shame to potty training in any way.

Well if you know when he needs to go as he is waiting at the bedroom door then put him on the potty and tell him to go poop then he gets to go to bed ..... I have a potty at the edge of my kitchen area which is right beside the bathroom and I am able to watch the child on the potty and the rest if the children in the playroom. Put him on and tell him to stay there .... If he has a melt down so be it stay strong.

If he knows that he needs to poop then he is old enough to do it in the toilet whether he likes it or not. We don't always get to do the comfortable thing and like it or not using the toilet is one of those rights of passage we just have to do. No more eating with the fingers - use a spoon, no more sucking on a bottle - here's a cup, no more soothers period..... the list goes on. You reach a point of being aware of bodily need then you take care of it appropriately - in the toilet.

If he is feeling that desparate then it is right at the edge and chances of him being able to hold it in for much longer are not likely so I would put him on the potty and then tell him bed after too.

right on playfelt .....

To Sunnydays - I think a difference in the case of the three year old is that he is totally aware of the need to poop and wants to do it right away but on his terms which are no longer acceptable. In the case of your daughter it sounds more like she hasn't gotten to the point of knowing when she is pooping till it is too late to do anything about it and that is still acceptable for her age.

acually he should sit on the potty because by bringing his knees up closer to his chest, it would be easier to poop instead of a toilet and have his legs dangling.

Put him on the potty when he's finished eating. I actually had the doctor tell us to do that with our son when he was having trouble with poop on the toilet/potty. When you eat, your brain sends signals that it's time to clear out some room! lol.

my daughter also didn't want to poop in the potty at three. I think it scares them (why,i have not idea!) She finally came around after a few months. I had to hold her hand while she pooped!