Evolution in the last ∼9.3 Gyr of the runs of various indicators of dynamical state, shown separately for each group class: (a) the fraction of surviving group galaxies relative to N_gal(z_ref); (b) the mass-weighted velocity dispersion of group galaxies; (c) the mass-weighted mean pairwise spatial separation among group members; and (d) the offset between the first-ranked galaxy and the group’s centre of mass, expressed in units of the expected group virial radius (Eq. (9)). Data points represent the mean values for each class, with the associated transparent shaded bands surrounding them indicating the standard error. The vertical solid and dashed lines in the panels mark, respectively, the Q₂, Q₁ and Q₃ quartiles of the distribution of turnaround times. Group classes are colour-coded as follows: single-BGG systems (blue), double-BGG systems (orange), and non-BGG systems (green).