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Identifying stars found in the Milky Way as having formed in situ or accretedcan be a complex and uncertain undertaking. We use Gaia kinematics and APOGEEelemental abundances to select stars belonging to the Gaia-Sausage-Enceladus(GSE) and Sequoia accretion events. These samples are used to characterize theGSE and Sequoia population metallicity distribution functions, elementalabundance patterns, age distributions, and progenitor masses. We find that theGSE population has a mean [Fe/H] $\sim -1.15$ and a mean age of $10-12$ Gyr.GSE has a single sequence in [Mg/Fe] vs [Fe/H] consistent with the onset of SNIa Fe contributions and uniformly low [Al/Fe] of $\sim -0.25$ dex. The derivedproperties of the Sequoia population are strongly dependent on the kinematicselection. We argue the selection with the least contamination is$J_{\phi}/J_{\mbox{tot}} < -0.6$ and $(J_z - J_R)/J_{\mbox{tot}} < 0.1$. Thisresults in a mean [Fe/H] $\sim -1.3$ and a mean age of $12-14$ Gyr. The Sequoiapopulation has a complex elemental abundance distribution with mainly high[Mg/Fe] stars. We use the GSE [Al/Fe] vs [Mg/H] abundance distribution toinform a chemically-based selection of accreted stars, which is used to removepossible contaminant stars from the GSE and Sequoia samples.

Selecting accreted populations: metallicity, elemental abundances, and ages of the Gaia-Sausage-Enceladus and Sequoia populations