I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
What you're describing falls under the criminal nuisance statute, which does make landlords or owners of a property liable unless there's evidence that they took steps to abate the nuisance. If the tenants are found guilty of using the premises for a criminal nuisance, it voids their lease. The definition of criminal nuisance includes "A material annoyance, inconvenience, discomfort, or a tangible injury occurs to neighboring properties or persons, and which a court considers objectionable under the circumstances..." Title 10, Del. Stat., Section 7103. The landlord may think they're not responsible, so if you haven't already, you can try sending a letter via certified mail that includes a print-out of the statute. But you also have the ability to name the landlord in an action for private nuisance, which may be faster than waiting for them to get around to taking action against the tenant.
You can also call the police and report the tenants for breaking and entering and trespass. You can also sue them for trespassing, property damage, and to get a restraining order preventing them from entering the property or speaking to you. If the words they're yelling are threatening or obscene, then you may be able to include disorderly conduct charges, and you can also add that to the nuisance suit. Under Delaware law, parents are responsible when their children intentionally damage or destroy property, so you can name the parents on the law suit in addition to the children. If the parents work, you may be able to use a judgment to attach a portion of their earnings.
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