The idea is that one pane of glass is a different thickness as the other... thus disrupting sound waves.  

She needs to deal with the people staying in her apartment disrupting everyone, whether they're her kid and his friends or not. 

I also let them know that they are disrupting our business and causing themselves to stand out as a bad customer/tenant.

My tenant has been there for approximately 2 months, and the upstairs tenants have been increasing disruptive and hostile to my tenant.

I know that might disrupt some things and I might have discussed these two options with the renter in the very beginning so they know there's some sort of expectation but this would likely be my plan of action.

My question is what do you think the best route would be to get rid of the disruptive tenants?  

Did the tenant display disruptive behavior?

If guests are found to have had an event/party without host’s permission, guests will be responsible for extra cleaning charges, and if disruptions cause complaints guests will be asked to vacate the property immediately and your reservation will be canceled without a refund.- Third-party bookings are not allowed unless agreed upon between the host and the guests in advance.

We were seriously considering going with his plan, and still may, but our progress on this step was disrupted by some medical issues, then by our decision to move from the balmy climate of So Cal's desert, to the balmier (IMO) world of Atlanta. 

OTOH, the bubble and all the disruption afterward makes it difficult to predict where we might end up.