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Strongly correlated rare-earth materials have been heavily studied because of their rich magnetic behavior which can be tuned via the application of pressure. Intermediate valence compounds are particularly interesting, since pressure can favor either a non-magnetic state, as in Ce-compounds, or a magnetic state, as observed in Yb-compounds. Because the rare-earth valence plays such a crucial role in determining magnetic properties, it is imperative to understand both the underlying physics and how to tailor materials to exhibit the desired valence configuration. With this goal in mind, we have performed a comprehensive structural and valence study of the YbNi(Ga,In)₄ system. We have measured the pressure dependence of the Yb-valence up to 42 GPa in YbNiGa₄ and up to 27 GPa in YbNiIn₄ via x-ray absorption spectroscopy (XAS) and resonant x-ray emission spectroscopy (RXES). Additionally, we have performed x-ray diffraction studies on YbNiGa₄ and YbNiIn₄ in excess of P = 40 GPa. We successfully tuned the Yb-valence from n = 2.15 in YbNiIn₄ to n = 2.6 at P = 42 GPa in YbNiGa₄.