Try a wet flannel, less stressful than being put in water
m and t are so fluffy underneath i've given up wipes and invested in a good sharp pair of hairdressing scissors. snip snip, all gone.
I found that toilet paper to get the worst off, then a flannel worked best. I was concerned about using baby wipes in case they irritated.
Oh I don't want you to think I was having a dig. I know there are lots of reasons why a bun's bum can get messy. Hope Lily forgives you soon!!
ha! matthew's face when i check his bum! "i say, young woman...that's a bit far!"