Has one of the nuns change him
From Create Your Own Story
"The mommies can change you and you can feel all better," said Kirsty. She noticed my hesitance. "I could change you if you want me to."
He mulled over it for just a moment and decided to take the former.
"N-No, I'll let them do it." She seemed satisfied with the answer, giving him a bright smile and tugged on his hand, escorting him back to the castle.
He struggled to keep himself composed. He could feel the mess of his poop in his diaper, drooping between his legs. Strangely, he could smell the poop and was not disgusted by it. It actually smelled pleasant, almost sweet like chewing gum, but decided not to pay no mind. He could feel the warm, urine-soaked front rub against his groin. He was almost aroused by the feeling, and would have had an erection if he wasn't so mortified with himself.
He was brought over to the nuns, or "mommies" as Kristy called them. Both of them were changing Jamie and Sophie. Sophie's diaper was wet, and had already had her new, dry diaper applied onto her as she got up and toddled away. Jamie's shirt was pulled up past his belly button and had his legs up, his butt being wiped by the nun with wet-wipes as his poopy diaper was being balled up and placed into a wall trashcan. Despite being old enough to be potty-trained, Jamie did not seem to mind being handled like a baby.
The nun who changed Sophie noticed Daniel and got up, grabbing him like before. Daniel squeaked in surprise but was too nervous to react. He felt the mess in his diaper squish around, spreading across his diaper and his butt as he sat on her forearm. She gently sat him down on his back as she undid the tapes on his diaper. He was shocked; he tried undoing the tapes of those diapers before and they would not even budge, but she was able to undo them without any struggle. Jamie got up next to him, his new diaper reapplied as he ran off to join his sister as the nun lifted his legs up for him, revealing his messy butt to anyone who was watching.
Daniel put his hands to his burning-red face as she wiped his entire diaper-area with wet-wipes. She threw the wet-wipes and the used diaper into the same trashcan as before and applies an identical onto him.