First, it's important to understand Airbnb's policies around guests under 18 years old. According to Airbnb's Terms of Service, users must be at least 18 years old to create an account, book a reservation, or host a listing. However, there are some exceptions to this rule. For example, users between the ages of 13 and 17 can have an account if they are added to a booking by a parent or legal guardian who is also a user on the platform.
In terms of whether to accept or decline the reservation, it ultimately depends on your comfort level and the specific details of the inquiry. If you feel comfortable renting your cottage to a group of 17 and 18 year olds, and you are satisfied that they will respect your house rules and treat your property with care, then you may choose to accept the reservation. However, if you have any concerns or reservations about the group, it may be best to decline the reservation.
One important thing to keep in mind is that Airbnb has a strict policy against parties and events, regardless of the ages of the guests. If you are concerned that the group may be planning a party or event during their stay, you may want to communicate your house rules very clearly to the guest and consider setting some additional guidelines or restrictions to ensure that your property is not damaged or disrupted.
Ultimately, it's up to you as the host to decide whether to accept or decline the reservation. Consider your own comfort level, the specifics of the inquiry, and any concerns or risks that you may have before making a decision.