Total Order Broadcast protocols are important tools to ensure coherence across distributed systems. Contrarily to classical distributed systems, pervasive systems bring important constraints related to the performance and reliability of the network and the availability of the devices (laptops, PDAs and cellular telephones). We propose in this paper a self-stabilizing group membership service that helps a token-based Total Order Broadcast protocol to progress in a volatile environment. This group membership service is organized in two hierarchical levels so that unstable nodes are kept in the group without interfering with the Total Order Broadcast protocol. As a result, we avoid expensive membership view changes while keeping the coherence among the nodes.