The integration of distributed generators, combined with the resistive characteristics and low short-circuit capacity (SCC) of feeders, can lead to voltage and power oscillations in distribution networks. This study investigates the dynamic behaviours of such systems, identifies the causes of these oscillations, and proposes two fluctuating power allocation strategies using advanced flexible interconnection devices (FIDs). An FID consists of multiple coordinated voltage source converters (VSCs) and regulates AC voltages to maintain stable system operation. Two representative scenarios are investigated: 1) a flexible interconnected distribution network with normal feeder connections; and 2) a network incorporating low-SCC feeder connections. The proposed strategies perform: 1) coordinated power adjustment and sharing between FID-VSCs and feeders to mitigate active power fluctuations, with each converter controller adjusting its output based on available capacity; and 2) minimizing feeder voltage oscillations and stabilizing system operation through coordinated reactive power support from the FID, while accounting for feeder SCC limits. An FID-enabled 10 kV flexible distribution network with a wind generator is modelled in PSCAD/EMTDC to validate the strategies, demonstrating continuous and steady operation, as well as appropriate power allocation under different conditions. The results show that, the proposed strategies increase converter utilization, improve active power transfer capability, and reduce voltage and power oscillation risks.