Previous multicast schemes for MANET (mobile ad hoc networks) are mostly classified as tree-based schemes and mesh-based schemes depending on their multicast delivery structure. Tree-based schemes cannot cope with network mobility due to frequent tree reconfiguration. On the other hand, mesh-based schemes waste unnecessary resource due to delivery along multiple paths. We propose to use an overlay multicast to handle network mobility efficiently with minimized resource. In our scheme, DDT (data delivery tree) can remain static as long as unicast route between members that are related to data forwarding remains reachable. Thus, it can not only minimize the effects of network mobility, but also bring about low additional control overhead. Such distinct advantages are specifically evaluated through the results of the simulation.