Same system as in Figure 1, but with mutual gravitational interactions among all four planets. The initial longitude of pericenter of each CBP’s orbit is randomly chosen in the range [0 − 2π]. The eccentricity of the planetary orbit grows significantly, even for the planet that does not undergo resonant eccentricity excitation in isolation. The resulting orbital crossings trigger strong interactions between planets, which reshape the orbital architecture and lead to either an ejection event (left panel) or a collision event (right panel).