Interconnecting microgrids in LV power system presents appealing features such as self-healing or power quality. When networked microgrids are not connected to a strong utility grid, their Point of Common Coupling (PCC) voltage and their power reserves vary with the operating point. An external droop control architecture is proposed that allows active and reactive power sharing among the different microgrids, thereby stabilizing the system frequency and PCC voltage, and the maximum achievable droop gains are supplied. Next, the design of appropriate primary controllers for the Distributed Energy Resources inside each microgrid allows to achieve a specified aggregated external droop controller at the connection point with little communication requirements. This methodology is applied to a modified CIGRE benchmark and shows good results while keeping a standard decentralized control architecture.