Questions about senior dog & diapers

Hello everyone! I don’t actually have a dog but I do keep a family member’s dog semi-frequently. He’s getting older and has had some issues with a recurring UTI that is seemingly resistant to antibiotics. He is currently on medication that is helpful, but he is still leaving pee dribbles here and there and having a hard time making it outside before he pees in the house.

I got him some diapers and they’re working well but I was wondering if I need to wipe him with baby wipes or a washcloth after he pees in the diaper? I don’t want to irritate his skin either way—by either wiping or not wiping. I’m just not sure about the correct protocol for that. His owners don’t currently use diapers at their house, otherwise I’d ask them what they do. So is there a standard way to go about it? Wipe or no wipe? And should I be leaving the diaper off at times so he can still lick/clean himself? Thanks in advance for any advice.