Gut, I don't know if the guilty party will feel guilty over a week of grounding. If it was that girl who already lied, I can just about lay odds that she won't care. I hope that you sit down with them as you let them back into your home and lay down your law (rules) of what is allowed and what is not allowed, and what you will do if the rules are broken. My kids and their friends always appreciated my honesty. I think their parents did, too.