Thankyou Stepmom, you are exactly right.
While my daughter is usually very good about letting me know things way in advance, (The dance issue was not her fault. My X threw at her that I must pick her up or she couldn't go.) my son really doesn't have the capability. He is ADHD and basically lives hour to hour. I have my doubts that he could tell you what time he starts school in the morning, much less what time a party is next week.
My son had an appointment with his psychologist 2 days before the party. I sat in a waiting room for 15 minutes with this "man". Did he advise me of the party? NO!
I have on several occasions sent letters to the X advising him that he needs to contact me in advance regarding any activity that our children might have during my visitation. I have full documentation in recorded phone calls that the ONLY time my X will contact me about anything is when it is beneficial to him. And usually that is only when he needs a babysitter. These phone calls also show that I am repeatedly advised at the last minute of things during my visitation time.
Is there anything the courts can do to stop this? I doubt it. It is my children, my son mostly, that are suffering. He doesn't see it that way. He sees it as hurting me. All I can do is continue my documenting.