Ability to recover R_birth for subhalo 560751 with age and [Fe/H] uncertainties added (15% and 0.05 dex respectively). Left: The age–metallicity relation for this subhalo with the true evolution of $\widehat{[\mathrm{Fe}/\mathrm{H}]}(R_{\mathrm{birth}}$ = 0 kpc, τ) (black line) and estimated evolution assuming the projected galactic center is always increasing in [Fe/H] (red line). The second, third, and right panels show the R_birth distributions for mono-age populations of solar neighborhood (7.75 ≤ R ≤ 8.25) stellar particles for the true R_birth, R_birth inferred using the true $\widehat{[\mathrm{Fe}/\mathrm{H}]}(R_{\mathrm{birth}}$ = 0 kpc, τ) (Inferred_decR_birth), and R_birth inferred using the monotonically increasing $\widehat{[\mathrm{Fe}/\mathrm{H}]}(R_{\mathrm{birth}}$ = 0 kpc, τ) (Inferred_incR_birth) respectively. Inappropriately assuming a monotonically increasing metallicity abundance in the galactic center provides R_birth distributions that are non-physical and do not match the true distributions, whereas using the true $\widehat{[\mathrm{Fe}/\mathrm{H}]}(R_{\mathrm{birth}}$ = 0 kpc, τ) evolution provides a more accurate trend in how R_birth decreases with increasing age. Examining the R_birth distributions of mono-age populations in the solar neighborhood is thus a necessity in constraining $\widehat{[\mathrm{Fe}/\mathrm{H}]}(R_{\mathrm{birth}}$ = 0 kpc, τ) evolution.