Not tidying after themselves

Everytime we’ve been over at my in-laws for lunch and my SIL instead of telling her 2 children to tidy up she asks them if they can clean up after they go. And of course they say no! So they leave without cleaning up. It leaves my child and I to tidy up all the mess the kids made! I absolutely hate this, I make my 3 year old to take care of her toys, tidying up after use etc. so to leave the mess behind for my in- laws doesn’t sit well with me and not teaching my child right.

My FIL has mentioned before it’s important to do so but yet their daughter is being an entitled ass. I don’t know if I should say anything next time by maybe demanding all 3 kids clean up before anyone leaves?