Fractions of the in situ stellar mass of galaxies accreted via mergers versus redshift, decomposed by the baryonic mass of the other galaxies at each redshift. In effect, we split the orange curves of Fig. 5 into further components. We focus on dwarf, Milky Way, and group halos in the upper-left, upper-right, and lower-left panels, respectively. For reference, the lower-right panel shows the same analysis when combining all central galaxies resolved in the simulation. Overall, more massive centrals obtain a lower fraction of mass from under-massive structures in terms of their baryon content.