GridVine is a Peer Data Management System based on a decentralized access structure. Built following the principle of data independence, it separates a logical layer -- where data, schemas and mappings are managed -- from a physical layer consisting of a structured Peer-to-Peer network supporting efficient routing of messages and index load-balancing. Our system is totally decentralized, yet it fosters semantic interoperability through pairwise schema mappings and query reformulation. In this demonstration, we present a set of algorithms to automatically organize the network of schema mappings. We concentrate on three key functionalities: (1) the sharing of data, schemas and schema mappings in the network, (2) the dynamic creation and deprecation of mappings to foster global interoperability, and (3) the propagation of queries using the mappings. We illustrate these functionalities using bioinformatic schemas and data in a network running on several hundreds of peers simultaneously.