this is my honest opinion its what i would do not telling you what to do xoxo
but if shes coming into YOUR house then she needs to follow your rules especially as youve got other children picking up on the behaviour
would you let your children behave like that?
and taking stuff home??? she needs to learn that she cant always do that
maybe have one thing that she can take and bring back
i hope this helps
its a rock and hard place but maybe if it doesnt work out they could find someone more suited to their daughters needs????