Comparison of the best-fitting solutions regarding the treatment of metallicity for the case that includes the local Δν of the primary and the magnitude difference of the components in the figure of merit (Case D). The magenta solution only allows values where the metallicity of the primary equals the metallicity of the secondary (Case D1), while the royal blue solutions force both metallicities to be equal to the spectroscopic solution (Case D2). The cyan part only allows values in the range of 1σ around the spectroscopic value (Case D3). Symbols and colors are identical to Fig. 2.