Colleagues decide fate of De Vries and Buemi: Can they race?

In Formula 1, it is clear: the 20 drivers only compete in this championship and (barring injuries/illness) are present at every Grand Prix. In other classes, it is often different. Drivers in the World Endurance Championship regularly also compete in Formula E. This is usually fine, as the races are not run on the same days. Only this year, it's different. When the 6 Hours of Spa is scheduled for the WEC, there is a Formula E race in Berlin. That causes problems.