Custodial parent DWI how to inform NYS Family Court

My sons mother was arrested for a DWI resulting in personal injury May 2013. My son for over a year has talked about an accident he was involved in. He is 4 and I figured their was little truth to his story stating he was involved and that his "papa" picked him up prior to police arriving. I asked his mother about said incident multiple times and she simply said he was making things up. Just recently upon a Google search of her name I found her listed on the internet. I recently filed a FOIL request however the statement says he was not involved. Around the same time period he was dropped off for visitation with a "rug burn" on the inside of his arm near his elbow. During our divorce 8/2012 I did state she consumed multiple drinks every night and thought it was a problem. My concerns were dismissed as I had no evidence. She was granted the ability to move 2 hours from our home. What paperwork would I need? On what grounds would I file?