Upper panel: Simulated eccentricity evolution of the binary HIP 15429 under the influence of a tertiary outer companion with a mass of 0.5 M_⊙, inclination of i_out = 60°, and period ratio of ten during the first 10⁴ yr since the end of the mass transfer phase. Lower panel: Heat map visualising the maximum eccentricity excited in the inner binary as a function of outer companion mass and inclination. The heat map has been computed for a fixed outer to inner period ratio of ten. The white dotted line marks the region of parameter space where the inner binary’s maximum eccentricity exceeds 0.5. An increase of the outer companion’s period shifts this line to slightly lower inclinations, shown for P_out/P_in = 20 and 50 with solid and dashed white lines, respectively. The black hashed region indicates the parameter space for which the probability of observing e >  0.5 for the inner binary at any given point exceeds 20%.