My question involves an injury that occurred in the state of: Michigan

My family owns vacation property on a lake in Michigan. The property is in the name of an LLC and we have written by-laws for the property rules. One of our by-laws states that there is to be no drugs or underage drinking. Anyone who uses the property has to sign a form stating that they have read the by-laws.
My question is this, if one of the owners children go to the property with out a parent and they bring friends with them and they are under age (21 is our drinking age, and we will say those attending would be over 18), what is our liability should either one of these things happen:
The cops show up and find minors in possession?
Someone gets hurt on the property or leaves and gets into an accident?

If they have signed the by-laws stating they know they can not drink, and we are not providing the alcohol or aware that drinking is taking place...are we free from risk?