Distribution of brightness versus time for GRB afterglows associated with ET-detectable NSNS (left panel) and BHNS (right panel) mergers. Solid and dashed contours contain 50% and 90% of the peaks, respectively. Red, green, and blue colours refer to the radio (F_ν at 1.4 × 10⁹ Hz), optical (AB magnitude at 4.8 × 10¹⁴ Hz), and X-rays (νF_ν at 1 keV), respectively. The coloured circles are the observed data of GRB170817A (Makhathini et al. 2021) at the median distance of our population. The grey lines in the background are a random sample of optical light curves from the underlying population. We assume for both the populations the same jet half-opening angle, θ_j = 3.4 deg. In the BHNS panel, we also show with orange solid lines the 50% contour for radio peaks when assuming θ_j = 15 deg.