When it comes to co-parenting there has to be communication. There was a tiny breakdown in communication with my ex and myself today. Everything ended up working out, but it did bring this matter to mind.
Once you have kids, communication is key. Me and my ex are in a co-parenting situation as we ended up divorced. Now our situation is a little more extreme then most. We split everything 50/50. And I do mean everything. We both visit the kids everyday, we go out to dinner once a week as a family unit. You could make a reality show about our co-parenting model. Communicaton is what has enabled us to make this work.
If I am going to pick them up a little late, I need to make sure I call or text as soon as I know I will be late. Even if it is only going to be 10 minutes late. If I need to swap a visitiation day because of a work related issue, I need to let her know as far in advance as possible. If something is going on at school, I need to keep her in the loop as well. If I am able to do this for her, she will do the same with me. Anything that is going to change the normal rituals that we have, must be communicated with as much notice as possible. It comes down to respecting the other persons time and hoping that they will do the same for you.