Stability analysis of the K2-157 planetary system. For fixed initial conditions (Table B.5), the parameter space of the system is explored by varying the orbital period and eccentricity of K2-157 d. The step size is 0.02 d in orbital period and 0.0025 in eccentricity. For each initial condition, the system was integrated over 10⁴ yr and a stability indicator was calculated, which involved a frequency analysis of the mean longitude of the inner planet. The chaotic diffusion is measured by the variation in the frequency. White-yellow points correspond to highly unstable orbits, while red points correspond to stable orbits on Gyr timescales. The magenta dot corresponds to the best-fit solution (P_orb,d = 66.50 d, e_d = 0).