What a truly stunning space @Cindy644
Would your place even accommodate having an extra 15 people on top of your guests sit down for dinner, do you have enough cutlery, plates, glasses, chairs? What about sofa's? What about bathroom space?
I would not allow this. Having 15 people over in addition to your guests is a party. @Cindy644
If they have co-workers and parents living locally, then they can host the party.
Just say that your listing is not suitable for use by so many guests and suggest some nice nearby restaurants they could consider.
To be honest your lovely space looks ideal for a party so you will attract those wanting to do so. Make sure your house rules say that only those who book and pay can be on the promises and that having guests on the premises who haven't booked is likely to lead to a cancellation of the booking.
If you have nearby neighbours also have house rules around late night noise, particularly outside.
Also do make sure you have CCTV to monitor use of your property and your own home insurance to cover short term lets as the Airbnb Guarantee has many exclusions.