Hello @Daniel1127,
You don't say whether the guests are using the Android or iOS app.
On the Android app I tried to book your listings for 1 guest for the 23rd to the 24th of May and it showed the number of guests as 1 when I tapped the "Book" button. I can then tap the "Guests" area of the screen and select 2 guests. The price then goes up by your extra person amount. It's not possible to tap to add more than 4 guests as that's your maximum for each listing.
I presume that Apple's iOS app has the same function.
If the group size the guests try to book is more than 4 then that's why they can't do it. If it's just 2 or three then they can do it and if they say they can't then just send them a request, by clicking "Send or request money" link on their reservation. You can insist that they accept that before you let them in.
If I were being cynical I'd say that they may be trying to avoid the extra person charge.
Steve.
