Education Law Questions? Ask an Education Lawyer
Thank you for your question.
Is the student objecting to the seatbelt?
You will have to ask for a review of the IEP.
The IEP is a legal document and if the student falls out of the chair because he or she was not belted in, the school can be sued for endangering the student by not complying with the IEP.
You can start by discussing this with the school administration and hopefully they can contact the parents and agree to modify the IEP.
I am sorry this may not be the answer you had hoped for, but it would be unfair to you, and unprofessional of me, not to provude accurate information.
I hope this information is helpful.