Complementary suspension device applicable between the hydro-pneumatic suspension systems of at least two wheels of a vehicle, which transfer the forces originating in said wheels to the aforementioned complementary device by means of displacement, and/or decanting, of the fluids of said suspension systems through the corresponding conduits, said device comprising two fluid distribution units connected in parallel by means of each joint conduit, between the hydro-pneumatic suspension systems of at least one pair of vehicle wheels, in such a way that for each pair of wheels the first distribution unit is capable of allowing the intake of fluid through the joint conduit with the suspension system of one of the wheels and, at the same time, lets fluid exit through the joint conduit with the suspension system of the other wheel, whereas the second unit only allows the intake of fluid through the joint conduits with the two suspension systems at the same time.