When a student doesn't attend school, the assumption for any educational delays is that they were not there to get instruction which is why are delayed. You are right that proving a disability caused school refusal is tough to do. If the family can afford to, my suggestion is a neuropsych eval. Some insurances will cover this. I've also heard of due process after a student has graduated. If the school's lack of Child Find caused the school refusal, there could be a case. With adult ed, disabilities need to be accommodated for so having an evaluation on which to base the accommodations the students needs would be helpful. I wish this student & their family luck in getting a GED & it opening doors to being a gainfully employed and productive adult.