If I’m hosting a visiting cat at my home, I will isolate him/her in a separate room from my cats. The food and litter box will be in that room. Depends on the visiting cat’s mood, I can either play with him/her, or give him/her more space. I fed my friend’s cats when they were away. I would wash the bowl, place new food, fill the drinking water, clean litter box. Also, I would stay around for a little bit, see if the cats are healthy. And if they are in the mood, I would play with them.