In a wireless sensor network, the virtual connectivity between nodes is a function of the keys shared between various nodes. Pre-embedding these key configurations in the nodes would make the network inflexible. On the other hand, permitting subsets of nodes to engage in a common key synthesis phase to create secure distributed connections amongst themselves, would decouple and conceal the information flow from the controlling centre. An intermediate solution is the notion of a centre driven key generation process through broadcast tokens, designed to extract different keys in different nodes based on some prior information stored at the nodes. As more tokens arrive, the virtual connectivity of the nodes are altered and the network evolves. This evolution can be distributed and can be controlled to converge to a certain specific connectivity profile. In this paper we present a framework and an algorithm which controls the simultaneous and distributed key release in different nodes, resulting in the creation of parallel virtual multicast groups. The design of the node shares and the supporting broadcast tokens have been discussed in conjunction with the process of balancing the spans of individual groups with spans of several coexistent multicast groups.