Dynamical map for the solution presented in Table 5 for a wide range of orbital periods and eccentricities of the outer planet b. Small values of the fast indicator log $\widehat{REM}$ characterise regular (long-term stable) solutions, while chaotic solutions are indicated by log $\widehat{REM}$ approaching 0. The black line represents the so-called collision curve of orbits, defined by the condition: a_b(1 + e_b) = a_c(1 − e_c). The vertical dashed black line shows the centre of 4:1 mean-motion resonance. The filled black circle with a white rim indicates the position of the solution with uncertainties for the outer planet b. The resolution for the plot is 401 × 201 points.