In order to extend the stay of a guest in house it can be done in the following ways:
Navigate to room chart
On the edge of the reservation, your cursor should change into the double arrow/ horizontal resize
Drag the until the new departure date
NebulaPMS will then give a confirmation box to confirm you are sure you want to change the departure date. Check the date is correct and click on Confirm
Open the reservation and navigate to the itinerary tab
Select the itinerary line to be extended
Click on the Edit button
Change the departure date and click Save

Please Note:

Add additional itinerary
This step may be utilised if the rate code does not have amounts loaded and the administrator is not available to assist.
Open the reservation
Navigate to the itinerary tab
Click on Add
Select Room Chart or Availability and make a reservation as you would normally
Click on Save
The reservation may have now become a Group Reservation if it was not already
Check out the old itinerary line and check in the new itinerary line
NebulaPMS will now have created a Master Invoice and there will be additional invoice per each room.
Optional: May transfer all charges to the Master Folio or new room or configure charge routing so that all charges route to a specific invoice in the reservation.