This chapter addresses the challenges of estimating harmonics in non-radial, medium-voltage distribution networks, which are increasingly common in modern power systems. It presents a novel methodology that improves upon previous approaches by considering the unique topology of meshed networks and optimizing the placement of power quality monitors. Through detailed simulations and sensitivity analysis, the chapter demonstrates how this method effectively estimates harmonic distortions even in the absence of direct measurements at all network buses. The approach is validated using a complex test network, showing its potential to significantly reduce the number of required PQ monitors while maintaining estimation accuracy, thereby offering a cost-effective solution for network operators.