[Mg/Fe]–[Fe/H] relation for retrograde (top), non-rotating (middle), and prograde (bottom) stars as selected in the blue, red, and orange rectangles in the top row of Fig. 5. The five most significant mergers are shown by colour-coded contours (75% density level), while the yellow contours correspond to the in situ stars. This figure shows that depending on the orbital properties, single merger debris can mimic chemically different substructures.