High- α model with evolving means and standard deviation for orbital circularity of the disc-like component. Left: Evolution of orbital circularity, and orbital circularity dispersion as a function of metallicity, capturing a gradual transition of a chaotic state (predominantly made of proto-Galactic populations) to a rotationally supported disc-like motion in purple and the orbital circularity dispersion evolution of halo is shown in orange. Right: Fractional contribution of disc phase (proto-Galaxy to high-α disc) (purple) and halo-like (orange) GMM components as a function of metallicity. In all the panels, the scatter points show the location of the knots chosen to run our model. The bands are 1 σ uncertainties on the converged weights, circularity, and circularity dispersions. The fractions are computed for an evolving Gaussian for the disc phase and fixed Gaussian for the halo phase when the MCMC is converged.