Halo mass recovery performance with DfL IIb. Distributions in the offsets from true-to-predicted M₂₀₀ values (δM₂₀₀), shown here for single galaxy groups (top panels) and multi-galaxy groups (bottom panels). In each panel the distributions in halo mass offsets are shown for the full group RF model (shaded histograms) and compared to the central-only RF model (open black histograms), both of which are outputs from DfL. Statistics are presented in each panel for the group model, followed by the central only model. In the case of single galaxy groups, the two distributions are very similar, as expected. However, for multi-galaxy groups, the two halo mass offset distributions are significantly different. The central-only RF models yield halo masses which are biased to higher values of δM₂₀₀ (lower values of M₂₀₀ predicted) and have a higher dispersion relative to the group results. Moreover, the full group RF models have significantly better agreement with the true halo masses from each simulation. This demonstrates the critical importance of incorporating the group information into the DfL pipeline and hence justifies the need for the two stage approach, discussed in Section 3.