Detecting coherence transfer in complex quantum networks is challenging under uncharacterized experimental conditions and with limited access to the system. Here, we use the coexistence of static and dynamic coherence to derive a nonlinear criterion for coherence transfer. The criterion applies even when the verification capabilities of checkpoint nodes are uncharacterized. It requires only minimal one-network output analysis, up to the number of output state dimensions. Each output requires only two-setting measurements of state populations, regardless of the network size. The criterion is general for both spatial and temporal networks, including those with multiple coherence sources, and applies to quantum transport in solid-state nanostructures. Experimentally, using entanglement swapping, we transfer polarization-entangled pairs in four- and six-photon entanglement networks. The criterion provides experimental evidence of coherence transfer in multi-photon entanglement networks. Our findings provide a practical tool for investigating the presence, role, or function of coherence transfer in quantum networks.