Based on Rayleigh's linear theory of capillary jets, a single unstable disturbance applied to the surface of a jet grows exponentially until it breaks the jet into droplets. In practice, however, droplet generators apply multiple-frequency perturbations on the surface of the jet, thereby causing unintended surface wave propagation. This phenomenon can occur in a frequency range where the disturbance components with different wavenumbers compete with each other for breakup. In this article, we study the interaction of disturbance modes and explore the opportunity for managing these structural influences. The goal is to suppress the resonance effects to control droplet size and spacing over a wide range of frequencies. By creating an input/output model that represents the actuator and solving an inverse problem, we can determine the input signals capable of yielding a single-frequency driving perturbation. We also present experimental results that demonstrate the feasibility of producing uniform droplets using a composite input signal.