  We have conducted an angular differential imaging survey with NIRC2 at Keck
in search of close-in substellar companions to a sample of seven systems with
confirmed planetary-mass companions (PMCs) on wide orbits (>50 AU). These
wide-separation PMCs pose significant challenges to all three possible
formation mechanisms: core accretion plus scattering, disk instability, and
turbulent fragmentation. We explore the possibility that these companions
formed closer in and were scattered out to their present-day locations by
searching for other massive bodies at smaller separations. The typical
sensitivity for this survey is \Delta K ~ 12.5 at 1". We identify eight
candidate companions, whose masses would reach as low as one Jupiter mass if
gravitationally bound. From our multi-epoch astrometry we determine that seven
of these are conclusively background objects, while the eighth near DH Tau is
ambiguous and requires additional monitoring. We rule out the presence of >7
M$_{\rm Jup}$ bodies in these systems down to 15 - 50 AU that could be
responsible for scattering. This result combined with the totality of evidence
suggests that dynamical scattering is unlikely to have produced this population
of PMCs. We detect orbital motion from the companions ROXs 42B b and ROXs 12 b,
and from this determine 95% upper limits on the companions' eccentricities of
0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on the
occurrence rate of additional planets with masses between 5 - 15 M$_{\rm Jup}$
outside of 40 AU in systems with PMCs is 54%.
