  The feasibility of extracting generalized parton distributions (GPDs) from
deeply-virtual Compton scattering (DVCS) data has recently been questioned
because of the existence of an infinite set of so-called ''shadow GPDs''
(SGPDs). These SGPDs depend on the process and manifest as multiple solutions
(at a fixed scale $Q^2$) to the inverse problem that needs to be solved to
infer GPDs from DVCS data. SGPDs therefore pose a significant challenge for
extracting GPDs from DVCS data. With this motivation we study the extent to
which QCD evolution can provide constraints on SGPDs. This is possible because
the known classes of SGPDs begin to contribute to observables after evolution,
and can then be constrained (at the input scale $Q^2_0$) by data that has a
finite $Q^2$ range. The impact that SGPDs could have on determining the total
angular momentum, pressure and sheer force distributions, and tomography is
also discussed. Our key finding is that scale evolution, coupled with data over
a wide range of skewness $\xi$ and $Q^2$, can constrain the class of SGPDs that
we studied and potentially make possible the extraction of GPDs from DVCS data
over a limited range in the GPD variables.
