Discrete element numerical simulations are used to understand how underplating, the subcretion of subducted sediments from the top of the downgoing plate to the bottom of the overriding plate, drives upper plate faulting and uplift patterns. Our simulations are modeled on processes occurring at Raukumara Peninsula, New Zealand, a location of proposed underplating. We also apply differential surface erosion, landsliding, and multiple versions of upper plate faulting, motivated by processes occurring on Raukumara Peninsula, to test how these factors affect the underplating system. We find that antiformal uplift generally occurs above an underplated body, accompanied by trenchward displacement outboard of the uplifting region. These two zones are separated by a normal fault, the location of which determines the relative amounts of uplift and horizontal trenchward displacement. Most of the tested factors in this system (landsliding, faulting, upper plate zones of weakness) have minimal effect on the form of uplift and overall system evolution. Differential surface erosion, however, shifts the zone of most rapid uplift towards the area with the greatest amount of erosion. This work suggests that, in the absence of a strong differential erosion forcing, antiformal uplift should be expected on Raukumara Peninsula but if differential erosion occurs, then asymmetrical uplift would be predicted. Both uplift patterns have been proposed by different workers there based on field measurements.