From left to right, the columns show the Isolated nonClumpy, Isolated Clumpy, nonClumpy+merger, and Clumpy+merger simulations. First row: projection onto the [O/Fe]–[Fe/H] plane, where red colors indicate regions of highest stellar density; the vertical lines delimit the interval −0.7 < [Fe/H] < −0.2, and the dashed horizontal line marks the cutoff separating the high- and low-α populations. Second row: [O/Fe] distributions within −0.7 < [Fe/H] < −0.2 for each simulation; the dashed vertical lines indicate the high- and low-α separation. Third row: V_ϕ distributions for the low-α population in the three simulations that form a bimodality. The inset panels show a zoom of the Splash region, and the dashed vertical line indicates the 〈V_ϕ〉 of each Gaussian fit. Fourth row: same as the third row, but for the high-α population. In the third and fourth rows, the red dashed vertical lines indicate the cutoff used to select the Splash population, accompanied by the exact V_ϕ adopted.