In order to mark a reservation as a group booking, in the reservation form change the booking type from Individual (default) to Group booking. 




Enter the Group Owner Name which is obligatory to mark the reservation as for the group. Then, remember to save the reservation.




You can see all your group bookings using the filter in Reservation View. Select the dates and Filters, uncheck individual bookings box to see only group bookings.





Check also:

Reservation window review

How to create a simple booking

Adding a Quick Booking

What the reservation status mean and which ones are changed automatically?

Where to find reservations and guests list