Modular backup fluid supply system

A system and method to allow backup or alternate fluid flow routes around malfunctioning components using removable, modular component sets. In one exemplary embodiment, an ROV establishes a backup hydraulic flow to a BOP function by attaching one end of a hose to a modular valve block and the other end to an intervention shuttle valve, thus circumventing and isolating malfunctioning components. A compound intervention shuttle valve is provided that comprises first and second primary inlets, first and second secondary inlets, and an outlet. A modular valve block is provided that comprises a directional control valve, a pilot valve, a manifold pressure regulator, a pilot pressure regulator, stab type hydraulic connections and an electrical wet-make connection.