Best fitting parameters for the complete spectroscopic sample of J1727 (see Fig. C.1). The left figure contains parameters associated with the absorption component, while the right figure shows the emission component parameters. For those parameters that are independent for each of the fitted lines, the following colour code applies: $\mathrm{H}\delta$ (blue), $\mathrm{H}\gamma$ (green), and $\mathrm{H}\beta$ (red). The black-dashed line in the top panel marks the systemic velocity reported in the text. Transparent points mark best-fit solutions where EW_abs is consistent with 0 within 3σ, and therefore consistent with a non-detection of BA. A similar line in the I_ratio panel marks the symmetric profile (I_ratio = 1). Units are [$\mathrm{km}\mathrm{s}-1$] for μ_abs, μ_em, σ_abs, μ_em, DP; and [$\mathrm{\AA }$] for EW_abs and |EW_em|.