Dynamic spectra (see explanation in Sect. 3.1) for the target systems’ H_α lines. Left: observed spectral time-series after spectra selection. Middle: background spectrum used as input for the RT module. Right: best fitting disc wind model (parameters summarised in Table 4). A black dashed line marks superior conjunction, while a red selection box denotes the region used for the calculation of ${\chi }_{\nu }^2$.