@Paul-and-Debbie0
If you are positive the guests know of your house rules then you will be confident if you need to confront them. One way to do this is to post a laminated copy inside the listing, point to it as you check the guests in and ****read it to them****.
I have a little introduction. I say to the guests 'I have an introduction for you and I have to do it in a certain order or I will forget something important.' I smile and joke a bit while saying that.
Then I invite them into the bathroom (which is TINY) and point to the bathroom wall and say 'Mr T (what we call the camper/RV toilet' is here to help you remember. The bathroom rules have a picture of Mr. T the celebrity on it. They smile. It breaks the ice for the 'RV toilet talk.'
Then we come out of the bathroom, I run through everything else while pointing to the items/features and the house rules that are posted about each item.
Since I started doing this, zero issues. Before that, well, let's not talk about it.
So if your House Rules are posted with bullet points, you go up to the guests as soon as you realize an issue, point to the laminated sheet and glare at them. Most people are mortified to have been 'caught' and straighten up immediately.
In this incident, before they booked you might have emailed the house rules and pointed out that the limit of individuals present would be X and will that work for them. Or when the second car went up the driveway, you would have been right behind it. Once there are 50 people there you would have to involve Airbnb to call the registered guest and tell her to tell them to leave NOW. If you have a house rule in place, Airbnb will do that. If the person you reach won't do that, ask for a supervisor or call again in a few minutes and get someone else.
Police is only if you want them OUT NOW and plan to have them arrested if they won't go. Probably not the best idea if they are getting ready for a wedding, but would work fine if a young couple booked and it turned into a frat party.
Unless you know a police officer or a sheriff's officer that would just come and stand by you while you chat with the registered guest. In a friendly kind of way. Depending on your police force, sometimes they prefer to be there in case things get ugly, but are willing to just sit in the car and look annoyed while you deal with the situation.
If you know in your heart that your communication was clear enough for any one to understand, you will feel fine about enforcement.
Kerrin