Evolution of the amplitude of the libration of the resonant angle ζ_max − ζ_min (with respect to the evolution of the semi-major axis) once the co-orbitals are captured in a mean-motion resonance with another planet. The systems are the same as in Fig. C.2. Purple colour indicates that the co-orbitals keep converging toward the exact resonance (L₄ or L₅), while yellow indicates that the amplitude is increasing post-capture. White pixels represent the systems for which the co-orbitals were not in the intended resonance with m₃ at the end of the simulation. See the text for more details.