Since she has joint, she is allowed access to school and medical records and she can do that herself legally and you won't get nailed...it really is on her to send the copy of the decree and ask about the kids.
As a decent parent, you should keep her informed of your decisions on Drs. and illnesses. When it comes to medications...if she is a decent parent you both should talk about it and help the kid but legally it's on you to make final decisions.
In my state you must have a huge change in circumstance to return to court for stuff and be taken seriously.