Backtracked (and extrapolated) half-mass radii determined for bound (blue) and unbound (orange) stars 10 Myr into the past and into the future. The green dashed lines show the minima of the backtracked half-mass radius for unbound stars. Left: for NGC 6530 members. Middle: for Upper Sco members. Right: backtracked (and extrapolated) half-mass radii determined for the unbound members of subclusters of Upper Sco.