<human>: Hello, this is a throwaway in Massachusetts

 Someone I know (Call him Nate) is involved in the ownership of a building with two of his siblings (Mike and Peter). The building houses a company that the sibling's father (Aaron) created a long time ago and Mike was named president and given dictatorial majority of the company at some point. Nate was made vice-president and Peter was a middle-management employee. The building was split evenly between the 3 siblings. Mike and Aaron would constantly gang up and harass Nate, often times physically, but always mentally abusing him.

 Eventually Nate was forced to retire from this company and was given a pittance for his shares in the company whilst continuing his ownership in the building. Now, Nate is no longer present in the building yet collects rent, as he always has, but without a lease agreement from the other brothers. He has demanded a written lease agreement many times and has been rebuked every time, and the tenant owes many back payments.

Recently, Nate was reading a story about medical marijuana dispensaries being licensed in this state and noticed that the address of a proposed dispensary is the address of his building. 

I am wondering in what ways would Nate be able to protect himself from the inherent dangers involved in owning a building where drugs are being grown. (not that Nate or I are against medical marijuana, just that he doesn't want it in his building without being able to control any aspect of it). Also what amount of liability would Nate have if something happened in his building.

Also, it is assumed that his siblings vote en bloc on all matters.

Condense the text into a few key points
<bot>: Nate needs to know how he can limit his liability in the event that the building he owns becomes a medical marijuana dispensary without his permission.