Unresolved multiplicity fraction estimates from four literature studies as a function of our estimated unresolved multiplicity fraction f_b(q > 0.6), for the common open clusters between the two studies in each case. As a guidance for comparison, the equality line is drawn as a dashed grey line in each panel and the black dashed lines show the expected relation when a flat mass-ratio distribution is assumed. Top left: Niu et al. (2020). Top right: Jadhav et al. (2021). Bottom left: Li & Shao (2022). Bottom right: Li et al. (2022).