Honestly, just stop tidying up after them, leave the crumbs on the floor and the pee on the toilet seat. Do you have another toilet you can use, like an en-suite? Use that and leave the mess where it is. If they don’t care, why should you?
I had a similar issue with my stepdaughter, not quite as gross, but still frustrating. When she’d get changed, she’d throw her dirty clothes into the laundry basket all tangled up: tights, pants, leggings everything still inside out and rolled together into a ball. I told my husband I wouldn’t wash them until she learned to take them off properly. I’m not standing there untangling her underwear.
At first, he got annoyed and accused me of being spiteful and just not liking her, didn’t faze me one bit 🤣 For a while, he started untangling them himself because I refused to do it and didn't wash it as a result. Eventually, he got fed up and started telling her off about it. Sometimes she sorts them out now, sometimes she doesn’t. When she doesn’t? Her stuff doesn’t get washed simple as that.
I make it very clear: I’m not the housekeeper. I do general cleaning and laundry for the household, but it’s basic respect if your clothes are on the floor or inside out, they’re staying there. She’s 13, not a toddler.
OP, you really do need to put your foot down.
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