Hi, T....
Have your 2 older kids starting "hanging" with a new crowd over the past couple of years? You might want to check that out.
I would have to say that there are going to be CONSEQUENCES for their misbehavior. If they have cell phones...take them away. If they have access to the car (the 16 year old, anyway)...NO driving privileges. If they want you and your husband to buy something they *want*, DON'T. Make them earn the money. They can do that by doing the chores around the house that are assigned to them, WITHOUT COMPLAINING. Be reasonable with the amount earned, but not generous. (oh, and if they do complain, they get to do the chore for FREE) If you are finding that they are not doing homework assignments, contact the teachers and let them know you want to know about the assignments being given the kids (ask if they will email you with the info each week). Let them know that if they do not keep up with their schoolwork, they will be going to SUMMER school next year...NO exceptions!! If they have tv's, ps2's, and such stuff in their rooms, take them OUT. These children need to learn to respect you and their daddy, and the other kids are watching them, so if you don't get them straightened out now, you may end up going through this 3 more times! (And that does not sound like any fun to me!) Sorry this got to be so long...it's just all the ideas I could come up with to help you and your hubby. I'm not a therapist or a counselor, but these are things that I have just "learned along the way".
Feel free to email me at ____@____.com, or call me at ###-###-#### if you need to talk and "vent". Best wishes for you and your family!