Whale, what happened to the lessee? Did he move out or has he just not been seen around? I would be inclined to enquire about his whereabouts and to his well being considering what has been happening. Something is just not right here. Someone does not move out and continue paying rent unless he has won lotto. If he was living in a unit with his son and his two kids he obviously didn’t have the financial means to pay the rent for them in the past.
Couldn’t you take action against the owner for the noise and disruption caused by her tenant, even though you know he actually isn’t there? If the lease is still in the original name, can’t you send out notice to comply to this name and notice to the owner for their tenant to comply? If the lessee doesn’t comply, and he couldn’t if he isn’t there, his lease could be broken?
Something not right with all this. Why wouldn’t an owner be interested in their property? Perhaps the tenants are known to her? I feel there is more to this story.