Left: color–magnitude diagram of the background cluster WL J0447.7–2020. Objects located within an r = 80″ circle around the BCG of this cluster are marked as orange circles, exhibiting a distinct red sequence redder than that of A514 (red dashed line). Blue dots represent the sources selected in Section 3.4. Right: mass contours (yellow) and XMM-Newton X-ray emission (orange) overlaid on the color image of WL J0447.7–2020. Cluster member candidates are marked as white circles.