Predictions of the two-infall model by ES21 including errors in the chemical abundance and age determinations (synthetic model) for the [Si/Fe] (first row) and [Mg/Fe] (second row) versus [M/H] relations. The colour-coding stands for the normalised predicted total number of formed stars in the [Si/Fe] versus [M/H] (top panels) area covered by each hexagon. Gaia DR3 stars are indicated by empty hexagons. For Si the grey hexagons enclose between two and six stars, the light-blue between six and 20. Finally, blue hexagons contain more than 20 stars. In the lower panels, the numbers of Gaia DR3 stars contained in the hexagons for Mg is smaller by a factor of two compared to the Si plots (upper panels). In the left panels, only stars with ages younger than 1 Gyr are represented, whereas in the right panels the whole ages are considered. We also depict the chemical evolution line predicted by ES21 without considering any errors with the green lines.