@Kristen506 I handle broken house rules by asking guests to leave. If they showed up comfortable with breaking this rule, how well do you think they are going to treat your property? By not confronting them immediately upon finding this out, you've set the tone for a week of them disregarding the rest of your rules, which can include mistreating your property. Why have rules if you're not going to enforce them?
When I had guests who broke house rules, I didn't come to the CC asking for advice. I asked them to leave immediately and told them I'd be calling the police if they did not.