Mass fraction of the largest companion and the primary satellite, as a function of the primary satellite’s mass. Here we use the entire sample of group infall events for the Auriga level-4 resolution sample (in blue), and the smaller Auriga level-3 sample (in orange). The solid lines correspond to the median of the samples binned by the primary satellite’s mass, and the shaded regions are the 1σ ranges given by the 16 − 84% percentile range. The additional top panel depicts the normalised histogram of the primary accretion events’ mass.