Tony

In your simulation, Capella D is orbiting 37 AU from the AB pair, and Capella C is orbiting 11 AU from the AB pair. This is not correct. Capella C orbits 11 AU from the barycenter of the CD pair, and Capella D orbits 37 AU from the barycenter of the CD pair. The barycenter of the CD pair orbits 11,000 AU from the barycenter of the AB pair. It's tricky to set this up in Gravity Simulator, since the interfaces are designed for systems with up to 2 massive objects, but not 4. So to set this up requires doing some math, coming up with distances and velocities on your own, and editing the system using these cartesian coordinates. I'll try to put together a more detailed explanation later.
