  In this letter, we address the problem of re-targeting a commercial
under-actuated robotic system to a higher dimensional output task. Commercial
platforms are equipped with an on-board low-level internal controller that
provides the user some virtual references inputs and cannot be replaced. Such
controller may control in practice only a subset of the total
degrees-of-freedom of the system. Our primary objective is to augment these
systems by introducing supplementary inputs, attaining increased output
capability. Integrating such additional inputs into the control framework
introduces a layer of complexity, raising questions about the compatibility and
cohesiveness of the overall system. We derive necessary and sufficient
conditions under which it is possible to extend the controlled outputs by
adding extra inputs when one is forced to keep the internal controller
unmodified. We underscore the efficacy and universality of our proposed
methodology through the presentation of two relevant examples.
