RV curves and residuals (O-C) from individual observations of BD−11^o162 (upper) and Feige 80 (bottom). The RVs of the cool companions are plotted with green filled circles, and those of the sdO are shown as blue squares. RV error bars (1σ) obtained by MC simulations, as described in Sect. 3.1, are also included. The best Keplerian orbits simultaneously fitted (MS+sdO) are shown as solid red lines for the cool companions and dashed red lines for the sdOs.