Left: [Eu/Mg] and [Mg/Fe] of stars with [Fe/H] > −1.3. Symbols follow Fig. 5 (for in situ and Gaia-Enceladus stars) and Fig. 7 (for LMC, Sagittarius, and Fornax). One-zone chemical evolution models are shown with the thick black line (baseline model A: Eu from NSMs with the standard Chabrier IMF), with the thick gray line (model B: a constant delay time for r-process enrichments, which represents the scenario that Eu is produced by CCSNe), and with the thin black line (model C: top-light IMF). Models are shown with solid lines for [Fe/H] > −1.3 and dashed line for −2.5 < [Fe/H]<  − 1.3. Typical uncertainties in GALAH DR3 are shown in the bottom right. The red arrows indicate how stars move in this figure because of the uncertainties in [Mg/Fe]. Right: same chemical evolution models, but as a function of [Fe/H]. The blue solid line shows the baseline model A but shifted to higher metallicity by 0.5 dex to present a track that mimics the fast chemical evolution of in situ stars. The in situ model completely overlaps in the left panel and model B completely overlaps with the baseline model A in the [Mg/Fe]−[Fe/H] panel.