Difference in relative (apparent) age between the merger remnant and the original tertiary star directly after the merger of the inner binary, for four selected models. Negative values indicate systems in which the merger remnant appears younger (i.e. rejuvenated) than the original tertiary companion. Positive values correspond to systems where the merger remnant appears older. The dashed black line marks the transition between rejuvenated and older-appearing merger remnants. Only models that deviate significantly from the fiducial model are shown; those that are nearly identical are omitted for clarity.