V-band magnitude difference as a function of angular separation for the resolved orbits of WDs in Tables 1 and 2. Resolved WDMS are shown with blue circles and DWDs with green squares. The resolved orbits in triples and quadruples are shown with red diamonds. The resolved orbits in multiples mainly consist of a WD with an MS-companion (see Table 2). Overplotted are our empirical estimates of the critical angular separation s_crit. Our standard model of Eq. (6) is shown as the black solid line, our optimistic model as the grey dashed-dotted line (Eq. (7)), and our pessimistic model as the grey dashed line (Eq. (8)).