As the number of users of LTE-A grows rapidly, the operator faces the challenge of wireless resource scarcity. The device to device (D2D) communication has been regarded as a valid way to mitigate this resource scarcity problem. In the meantime, with the booming of video streaming services, the eNB needs to use multicast for better resource efficiency. When the eNB performs multicast to all receiving devices within its serving cell, it needs to consider the worst channel gain device for the multicast to be successful. In this situation, the eNB is forced to use a worse modulation scheme to serve all devices. In this paper, we consider using D2D communication to assist the eNB in doing multicast. Since D2D communication works in a short range, the original eNB multicast is broken into two shorter-range multicast segments and a better modulation scheme can be used for both segments, resulting in higher multicast throughput. On the other hand, in assisting multicast, a short-range D2D communication cannot serve all devicess in the same cell. Therefore we need an effective clustering scheme to group devices into multiple clusters, each with geographically close devices. This paper addresses the following issues: evaluating two candidate clustering algorithms, formulating the resource sharing problem of one cellular equipment with multiple D2D communication equipment, and maximizing SINR of equipment by optimization models. From the simulation results, we find that, when the cellular device shares the uplink resource with multiple D2D communication devices, it is possible to save more resources with slight loss of throughput for D2D communication.