It sounds like they are trying to save by not changing any more often than they absolutely need to. So why is she sending cloth wipes to you and not using them herself? Tell mom you need liners for the cloth diapers and cream for the bum and I know it makes a mess of the cloth diapers but the liner does help. Not much you can do for the child. Is there any chance they are using disposable diapers at home such as overnight or are they out all weekend here and there and using them. If the child reacts to the wipes then she likely really reacts to disposable diapers. You could just come out and ask How much time does childX spend in disposable diapers? By mom's reaction you will be able to tell if it is never, sometimes, etc. I'm sure. That is certainly the first reason to address. Next would be the need for cream to be applied at least a couple times a day such as bedtime and morning. Third would be trying to find out how often child is changed. Ask something like I'm really not sure how often I should be changing her diaper. How often do you change her after she goes home in the evening or on weekends. Assuming you get the answer that translates into not often enough then just make a comment back like oh ok that explains why she often has diaper rash in the mornings. She probably needs an extra diaper change (insert a suggested time here). Then change the subject. Your point has been made in general chitchat in a non accusatory way. Let mom take it the way she wants. But do not comment in the next few weeks if there is an improvement. Just know that mom took your advise. If you say it is better she may go back to her old ways.