David,
Your last scenario is illegal. Patients that receive insurance checks and fail to turn them over to us receive a stern warning. "Please note! We have been informed by your insurance company that you were paid $$ for services which were provided by us on (date). We have yet to been paid by you. Be aware, this is considered insurance fraud and is a criminal offense. Please remit the amount owed to us promptly or we will be forced to inform not only the legal authorities but your insurance carrier as well. " I have yet to have to follow though on this and I have yet to lose a patient over it. They know they are wrong.
