My stepson started smoking when he was 15. I didnt approved him. I never buy him any cig. I told him that he cannot smoke at my house. I am glad that I rid of him!
I don't really know how to convince kids not to smoke. Maybe take them to hospital and convince the doctors to show them patients who are dying from cigarette related illnesses?
I am sorry to hear about what you are going through, but I am glad to know you and your daughter are closer now. Hopefully you will get your son back soon, too. Good luck.