Candidate selection based on colours and proper motions, with each row corresponding to one of the three regions of interest. The panels to the left show the G_BP − J, G_BP CMDs. The middle panels contain the proper motions; the red rectangle indicates the zoomed-in region of the plot, which is shown in the right-hand side panels. New candidates (green stars) are accepted if their colours and proper motions overlap with those of previously confirmed members (orange diamonds); that is sources are located to the right of the grey line in the panels to the left and inside the grey ellipse shown in the right-hand panels. Precise equations are listed in Appendix A. Photometric members with discrepant proper motions are indicated with blue crosses. The average proper motion uncertainties are shown in the lower right part of the zoomed-in proper motion plots; for region C these values were multiplied by 3 for better visibility.