When parents split up or separate prior to the divorce being final, a number of problems often develop with regard to who will have custody and the parenting time for the other child. Without a court order, there is a wild west situation. Court order grant rights to both parents so without one, there are no real rights. There is nothing for the police or the court to enforce. Thus, parents who separate and operate without a custody order is asking for trouble. We have seen clients operate without a custody order for 5 years and then when there is a problem, there is nothing to enforce.
Of course, courts will generally go with whatever the custody arrangement has been in the past but this can be tough to show when both parents lived together and both worked. Thus, the lawyer for the client seeking custody will have to get into the details of who did what for each child.