On the left panel, CCF results for two single SMBHs and a simulated binary given by the spectra presented in Fig. C.4, as a function of different fractions of the total BEL luminosity in the blue part of the line. On the right panel, the corresponding time delays, i.e. the time shifts that maximize the correlation coefficient. Here, the monotonic decrease is less evident than in Fig. C.2 since the measured delays are smaller than the adopted observational time step.