Minimum DM mass of the total system M_tot versus concentration of the haloes. We plot 1 / c in favour of c to include the point-mass results at 1 / c = 0 (cases 0a, b; plotted as open and filled circle – blue online). Solid lines are the results using the mass-ratio of 1.8. Triangles are cases with radial velocity only and tri-stars with additional tangential velocity. Dashed lines show the results of equal mass haloes. Squares are radial-velocity-only cases and crosses have additional tangential velocity.