 This paper proposes three novel strategies for reconfiguring the formation of multiple unmanned aerial vehicles, UAVs, when their swarm scale changes due to emergency situations. These strategies include leader disengagement, follower detachment, and new member addition. To evaluate the effectiveness of the proposed strategies, a hierarchical belief rule base, BRB, based knowledge-based performance assessment model was constructed. Simulation results show that the connection retention rate, CRR, for the swarm communication topology under the three formation reconfiguration strategies can reach 67%, 90%, and 100%, respectively. This article was authored by Haoran Zhang, Guamling Zhang, Ruohan Yang, and others.