To the reader who wrote: "Pretty ironic this is also my first child, huh? Of course I've learned a great deal of patience and my other 3 children are not like him at all, quite the opposite actually."
I reply: It is even scarier when it is your oldest child. Misery loves company and our son did everything in his power to entice his younger siblings (and the neighbor children) to join him. He provided them with substances and other things that would curl your toes. He also constantly undermined our parenting. Whatever we told our children, he'd pull them aside and tell them how awful and unfair and twisted our rules and standards were. His younger brother was very lost for years and we nearly lost him physically because of it. He is finding it a long, uphill climb to get out of the hole his brother drug him into at a very tender age.
It was horrifying to watch the domino effect taking place in our family. We did everything we could, but it wasn't enough. We learned to take a harder line with the first two and have been able to save the younger ones from falling in line. Here are some of the things we learned:
I would recommend that you limit the influence this child has on the others as much as possible. It is not a good idea for him to be sharing a bedroom with a younger siblings where there is too much privacy and opportunity to "indoctrinate" them and share his substances if he is into them. I would recommend a very firm rule about him not being in their bedrooms and vice-versa, especially if you have a daughter! You don't know at this point what his potential for wrong doing is, so better safe than sorry. I wish I had learned that earlier, but I kept trying to give him the benefit of the doubt.
There is much you can do to protect the younger ones without sending your son a message of complete distrust. Rely on your parenting instincts.
I would recommend eliminating sleep overs. Just like with measles, you do not want to be responsible for your sick child infecting your friends' otherwise healthy children, and your sick child will try!
If you have good grandparents in the picture, enlist them to help you. They can reassure the younger ones that big brother is temporarily lost and that mom and dad are not over-the-top in their discipline, etc.
People kept telling us that sending the problem child away wouldn't help because he'd get into trouble where ever he was. This is true, and we didn't have any place to send him anyway, but in retrospect, I know that it would have saved the younger one if we had sent the older child elsewhere to live. We felt like he was our problem though, and that we shouldn't push our responsibilities off on anyone else, but hind sight is 20/20...
If your child has conduct disorder and you can afford it, boot camp or one of the other options for troubled teens is the best place if you have younger children.