Evolution of the amplitude of libration of the resonant angle ζ_max − ζ_min (top) and mean eccentricities (bottom) for co-orbitals (m₁/m₂ = 6) captured in a 4:3 MMR with an outer planet such that m₃/m₁ = 1 (blue), m₃/m₁ = 1.6 (purple) and m₃/m₁ = 2.5 (red). The solid lines show the eccentricity of m₂, while the dashed ones show the eccentricity of m₁. Both amplitudes of libration and mean eccentricities are taken over a single libration period. These trajectories correspond to 3 cases of the top-right panels of Figs. C.2 and C.3.