A right-angle sheet stager apparatus for merging multiple input sheet streams into a single output sheet stream includes one or more input channels and an output channel. Each input channel includes a transport surface and a staging surface. Each transport surface communicates with its corresponding staging surface at a transitional member interposed between the transport surface and the staging surface. Each transitional member includes an upper surface disposed at an elevation greater than an elevation of the corresponding staging surface. The output channel includes an output surface, and is oriented in a right-angle relation with respect to the input channels and communicates with the input channels at a merger location. The stager apparatus permits a sheet from the transport surface to enter the staging surface and overlap with a preceding sheet already present on that staging surface, prior to the preceding sheet's complete exit from the staging surface.