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We have conducted an angular differential imaging survey with NIRC2 at Keckin search of close-in substellar companions to a sample of seven systems withconfirmed planetary-mass companions (PMCs) on wide orbits (>50 AU). Thesewide-separation PMCs pose significant challenges to all three possibleformation mechanisms: core accretion plus scattering, disk instability, andturbulent fragmentation. We explore the possibility that these companionsformed closer in and were scattered out to their present-day locations bysearching for other massive bodies at smaller separations. The typicalsensitivity for this survey is \Delta K ~ 12.5 at 1". We identify eightcandidate companions, whose masses would reach as low as one Jupiter mass ifgravitationally bound. From our multi-epoch astrometry we determine that sevenof these are conclusively background objects, while the eighth near DH Tau isambiguous and requires additional monitoring. We rule out the presence of >7M$_{\rm Jup}$ bodies in these systems down to 15 - 50 AU that could beresponsible for scattering. This result combined with the totality of evidencesuggests that dynamical scattering is unlikely to have produced this populationof 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 of0.58 and 0.83 respectively. Finally, we find that the 95% upper limit on theoccurrence rate of additional planets with masses between 5 - 15 M$_{\rm Jup}$outside of 40 AU in systems with PMCs is 54%.

Searching for Scatterers: High-Contrast Imaging of Young Stars Hosting Wide-Separation Planetary-Mass Companions