Diagram of [Al/Fe] vs. [Fe/H] showing middle-stream AII stars highlighted by orange bullets (panel a). Panels a1, a2, and a3 present the same plot zoomed in around seq1, seq2, and seq3, respectively (see text), with lower-stream stars highlighted for reference. The best-fit fiducial lines are shown in red, with open and filled red symbols representing the 0% and 100% dilution points, respectively. Panels b, b1, b2, and b3, show the corresponding plots in the [Mg/Fe] vs. [Fe/H] plane.