Hey, maybe this will help.
He needs to learn how to fall asleep onhis own in his bed. It is hard at first. Who wouldn't want to be rocked to sleep? So let him get drowsy, and put him in his bed. (With my child I had a little music box and she had a "lovie". If he cries, go in, pat him, talk to him ,tell himit's ok, bu tOD NOT PICK HIM UP. Keep doing this adn space out the amount of time between weach return visit to console him by like 1 minute. Eventually he will learn that he is expected to go to sleep inhis bed. As dfar as the patrents go, they can fo whatever they want at night, it's thier sleep they will be missing. Are they home during the day when you watch him? IF they are, this is going to be a lot harder. you might tell them that you have been reading up on infant sleep and you'd like to try it for a while to see if it works. You are in a tough spot, for sure!