You have two choices :

1. Have as destination of this leg n°13 an intermediate airport of your choice, and continue the tour with leg n°14 by making a departure from the same airport of your choice to LFMN - Nice Côté d’Azur for the event.
2. To not do this leg n°13, and directly go to the leg n°14 to LFMN - Nice Côte d’Azur from the airport of you choice.