  The phenomenon of nonlocality without entanglement(NLWE) arises in
discriminating multi-party quantum separable states. Recently, it has been
found that the post-measurement information about the prepared subensemble can
lock or unlock NLWE in minimum-error discrimination of non-orthogonal separable
states. Thus, it is natural to ask whether the availability of the
post-measurement information can influence on the occurrence of NLWE even in
other state-discrimination strategies. Here, we show that the post-measurement
information can be used to lock as well as unlock the occurrence of NLWE in
terms of optimal unambiguous discrimination. Our results can provide a useful
application for hiding or sharing information based on non-orthogonal separable
states.
