Completeness C of member galaxies of real groups in simulated TNG100 clusters detected by DS+ groups. In all panels, the dashed red line indicates the average over all clusters, using the overlapping mode, and the solid blue line refers to the no-overlapping mode. The filled areas indicate one standard deviation. In all cases, the curves correspond to the stacking of all analyzed clusters. Left: C as a function of the richness of the real groups, corresponding to the number of galaxies detected in substructures. Center: C as a function of the real group cluster-centric distance. Right: C as a function of the time since group infall.