Fraction of the stellar mass in each galaxy at z_ini = 3 that contributes to the IGL mass at z_fin = 0 vs. the fraction of the final IGL mass that this contribution represents, categorised by group class. From top to bottom, panels correspond to single-BGG groups, double-BGG groups, and non-BGG groups, respectively. Point sizes scale with the stellar mass of the contributing galaxies at z_ini, while point colours follow the same scheme used throughout the paper.