Bring them to see a dentist, worse come to worse.
Otherwise, if milk teeth is a bit shaky already, get them to keep shaking the teeth so teeth can loosen and drop fast and also get them to bite into “hard” foods like apples so the biting into hard foods can further help to “dislodge” the teeth fast. That’s what the dentist taught my gal and I when her baby teeth refused to drop but was shaky and an adult tooth can be seen growing out already.