  The current theories of quantum physics and general relativity on their own
do not allow us to study situations in which the gravitational source is
quantum. Here, we propose a strategy to determine the dynamics of objects in
the presence of mass configurations in superposition, and hence an indefinite
spacetime metric, using quantum reference frame (QRF) transformations.
Specifically, we show that, as long as the mass configurations in the different
branches are related via relative-distance-preserving transformations, one can
use an extension of the current framework of QRFs to change to a frame in which
the mass configuration becomes definite. Assuming covariance of dynamical laws
under quantum coordinate transformations, this allows to use known physics to
determine the dynamics. We apply this procedure to find the motion of a probe
particle and the behavior of clocks near the mass configuration, and thus find
the time dilation caused by a gravitating object in superposition.
