He just pooped his diaper on the way here. Could you please change it?
I think he had a poop coming here this morning. Could I please ask you to change his diaper?
ーHe just pooped his diaper on the way here. Could you please change it?
「彼はここに来る途中オムツの中でウンチをしたので、オムツを替えてもらえますか?」
to poop one's diaper で「オムツでウンチをする」
on the way here で「ここに来る途中」
ーI think he had a poop coming here this morning. Could I please ask you to change his diaper?
「今朝ここに来る時にウンチをしたようなので、オムツを替えてもらえますか?」
to have a poop で「うんちをする」
to change one's diaper で「オムツを替える」
ご参考まで!