As you may know, I have two teenage daughters. They are 15 and 13.  I am having alot of trouble with them hanging out with the wrong people.  They think I am very harsh and don't understand their feelings.  We argue about this alot.  What do you suggest on how to get the upper hand on this matter?  I love my girls with all of my heart  and want them to have friends, but only the right kind. I don't want them getting on drugs, sex, or any other bad thing.  I want them to be very successful.