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The low-metallicity, kinematically interesting dwarf stars studied byStephens \& Boesgaard (2002, SB02) are re-examined using Gaia DR2 astrometry,and updated model atmospheres and atomic line data. New stellar parameters aredetermined based on the Gaia DR2 parallactic distances and Dartmouth StellarEvolution Database isochrones. These are in excellent agreement withspectroscopically determined stellar parameters for stars with [Fe/H]$>-2$;however, large disagreements are found for stars with [Fe/H]$\le-2$, withoffsets as large as $\Delta$T$_{\rm eff}\sim+500$ K and$\Delta$log\,$g\sim+1.0$. A subset of six stars (test cases) are analysed abinitio using high resolution spectra with Keck HIRES and Gemini GRACES. Thissub-sample is found to include two $\alpha$-challenged dwarf stars, suggestiveof origins in a low mass, accreted dwarf galaxy. The orbital parameters for theentire SB02 sample are re-determined using \textit{Gaia} DR2 data. We find 11stars that are dynamically coincident with the \textit{Gaia}-Sausage accretionevent and another 17 with the \textit{Gaia}-Sequoia event in action space. Bothassociations include low-mass, metal-poor stars with isochrone ages older than10 Gyr. Two dynamical subsets are identified within \textit{Gaia}-Sequoia. Whenthese subsets are examined separately, a common knee in [$\alpha$/Fe] is foundfor the \textit{Gaia}-Sausage and low orbital energy \textit{Gaia}-Sequoiastars. A lower metallicity knee is tentatively identified in the\textit{Gaia}-Sequoia high orbital energy stars. If the metal-poor dwarf starsin these samples are true members of the \textit{Gaia}-Sausage and\textit{Gaia}-Sequoia events, then they present a unique opportunity to probethe earlier, more pristine, star formation histories of these systems.

Chemo-dynamics of outer halo dwarf stars, including \textit{Gaia}-Sausage and \textit{Gaia}-Sequoia candidates