In this paper, we proposed a three-tier platform for providing group streaming service over mobile network environments with Fixed Mobile Convergence (FMC) techniques. The upper layer server takes responsibility of Quality of Service (QoS) computing and scheduling for serving heterogeneously grouped streaming requests. The middle layer servers take care of streaming packets' collection, packetization, and transmission in real time. The low layer servers are allocated on public transportations for dealing with the multiplexed streaming packets' depacketization and distribution. In order to efficiently utilize bandwidth during group streaming services, we developed an efficient MSE-based multiplexing mechanism for analyzing and scheduling multiplexed streaming packets' transmissions. Comparing with traditional method of establishing direct end-to-end connection for each streaming request, the performance results of the proposed platform demonstrate that the developed multiplexing mechanism can reduce almost 40% variation of required bandwidth, and it can successfully serve grouped streaming requests in an efficient way.