I supply wipes (easier to not have 5 different kinds floating around) and parents supply diapers. I bring them the new diapers every time I notice they're getting low--usually when it's going to be less than a week's worth (most of my parents take a few days to remember the diapers).

For washing hands and faces on those too little for the sink (I'm lazy...) I bought a bunch of baby washcloths and keep them in the kitchen drawer. I use one for each kid and wipe of hands, face, and table/highchair. It works really well.

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