  We consider ultralong-range polyatomic Rydberg molecules formed by combining
a Rydberg cesium atom and a ground-state RbCs molecule. We explore the regime
where the charge-dipole interaction due to the Rydberg electron with the
diatomic polar molecule couples the quantum defect Rydberg states Cs(ns) to the
nearest degenerate hydrogenic manifold. We consider polyatomic Rydberg
molecules in states which are amenable to production in optical tweezers and
study the influence of nonadiabatic coupling on the likelihood of their
formation. The decay rates of the vibrational states reflect the interference
signature of wave function spread in different coupled potential wells.
