  In a binary system, the gravitational potential of the primary black hole may
play an important role in enhancing the fallback accretion onto the lighter
compact object newly formed in the second supernova explosion. As a result, the
final masses of the binary compact objects would be correlated, as suggested
recently by Safarzadeh \& Wysocki. In this work, we analyze the mass
distribution of four gravitational-wave events, which are characterized by both
a small mass ratio and a low mass ($\leq 5M_\odot$) of the light component, and
find tentative evidence for a mass correlation among the objects. To evaluate
the feasibility of testing such a hypothesis with upcoming observations, we
carry out simulations with a mock population and perform Bayesian hierarchical
inference for the mass distribution. We find that with dozens of low mass ratio
events, whether there exists correlation in the component mass distributions or
not can be robustly tested and the correlation, if it exists, can be well
determined.
