It is now possible to modify pairings.
In order to modify pairings you need to:
Selected flights are displayed on the right-hand side of the 'PAIRINGS' tab view.
The following changes can be made to pairings:
As you can see in the screenshot on the right-hand side, there are selected 3 flights from the schedule.
In 'Add flights' section we add a return leg for these 3 flights. Once the flight is added and saved it shows in the 'SCHED' view (marked flights in the below screenshot)