I have been trying to treat him like the mailman. Sometimes however he tries to give unsolicited help or advice and that drives me up a wall. An example is a couple of weekends ago, I was away for the weekend with my youngest but the oldest D was still at home. She was going to take care of the pets. Well she didn't get home from a friends soon enough for his liking, so he let himself into my house to feed them and let the dog out. I had to find this out from my D though. I told him he couldn't just let himself in. He said fine the dog could just poop all over the place. I told him well that would be my problem wouldn't it. If he had called I would probably not have had a problem with it.
As far as babysitting, that is written into the divorce decree. We each have the right of first refusal. I have to call him first if I need a babysitter and vice versa. I did that so he wouldn't be able to leave my D with a girlfriend in the future.