Reasonable people share contact information so that the other parent will be able to communicate with their children.
Reasonable people work together to raise their children.
Reasonable people keep their children out of their "adult" conflicts.
Reasonable people co-parent together and raise healthy, happy children.
Reasonable people recognize that they will be co-grandparenting.
Reasonable people put aside their anger & eventually find a way to be civil to one another.
If your children were in an accident or there was some sort of emergency, I'm sure you would want to be called.