Hi NL3, I'm so sorry you and S4 are going through this. OM sounds like a real winner. I see your point about why get an attorney in the first place if they will ignore the documents however for piece of mind, have you talked to one? Most consult for free. Have you documented some of what is going on other than on here? I wonder if the court would want to give you full custody based on the extreme circumstances. Something to consider. If S4 is already being impacted, its worth a consult and some charges to make sure you and him are protected.
Get an attorney. Like now. Why? Some courts will allow the appointment of a guardian ad litem who will basically be the child's attorney to represent their best interest. If being around the AP causes the child stress, the court could craft a custody arragement to alleviate the situation by ordering certain restrictions on custody. If she violates them it could be grounds to change the custody arrangement. i.e. lose physical custody of her child. You've got to get some evidence that it's not in the "best interests of the child" to be around the AP.
The custody orders are a binding agreement that she can't just decide not to ignore. She could get into some major league trouble for violating the order. And the order better say for sure that he AP is NOT authorized to care for the child.
She has to decide if she loves her AP more than her son.