Division of the MDF of the Thamnos substructure (see Fig. 4 bottom panel) into two distributions to identify the ‘true’ Thamnos component and the contamination from in situ stars (left panel) and MDF, SFH as predicted by the model built for Thamnos progenitor presented in Section 5.1 (two rightmost panels). In the left panel, the ‘true’ Thamnos distribution traced by observation is labelled with ‘distr1’ (dashed blue line), while MW in situ contamination would be represented by ‘distr2’ (dashed red line).