As a manager, you can create reservations for resources even when they are no longer available.
Open the order cart, select the Overbook option, and create the reservation.
You can also enable or disable the Overbook option directly on the reservation form.
If a reservation exceeds the limit, an Overbook warning will appear in the order.
To confirm the order, open the Manage tab. Uncheck the With availability and pricing validation checkbox. Then click Process.