The below options are available in the 'Settings' > 'General Settings' > 'Crew planning' tab:
It is possible to exclude a crew member assigned to 'Line Training' / 'Line Check' from the basic crew assigned to the flight.
Once the first two options are selected, assigned to a flight crew undergoing 'Line Training' / 'Line Check' will not affect the color of the flight indicating the crew composition in the 'Crew Timeline'.
As presented in the example, the aircraft is set to a minimum cockpit crew of 2. On the first sector, one of the crew is assigned to the 'Line Check' duty (indicated by the purple triangle) therefore the first of the sectors is highlighted yellow, indicating the partial crew assignment. The second sector is highlighted green indicating full crew composition since there is no training assigned.
Selecting the third option will activate the possibility to acknowledge changes in OPS and in the crew mobile app.