  In the present work, using the recently introduced framework of local
geometric deformations, special types of vector fields - so-called hidden
Killing vector fields - are constructed, which solve the Killing equation not
globally, but only locally, i.e. in local subregions of spacetime. Taking
advantage of the fact that the vector fields coincide locally with Killing
fields and therefore allow the consideration of integral laws that convert into
exact physical conservation laws on local scales, balance laws in dynamical
systems without global Killing symmetries are derived that mimic as closely as
possible the conservation laws for energy and angular momentum of highly
symmetric models. The utility of said balance laws is demonstrated by a
concrete geometric example, namely a toy model for the binary merger of two
extremal Reissner-Nordstr\"om black holes.
