Your parents should consult an attorney directly and privately to determine how cosigning the loan might affect them legally. Not only when it comes to your financial aid but in every aspect. It is a very serious matter especialy ifthey plan to lie on the application.
This answer is not intended to replace a consultation with an attorney and does not create an attorney-client relationship. Please do not contact me expecting additional free advice. If you contact me privately, I will email you an invoice for a consultation and will advise you only after the invoice is paid. Thank you.