This demo presents Hyperion, a prototype system that supports data sharing for a network of independent Peer Relational Database Management Systems (PDBMSs). The nodes of such a network are assumed to be autonomous PDBMSs that form acquaintances at run-time, and manage mapping tables to define value correspondences among different databases. They also use distributed Event-Condition-Action (ECA) rules to enable and coordinate data sharing. Peers perform local querying and update processing, and also propagate queries and updates to their acquainted peers. The demo illustrates the following key functionalities of Hyperion: (1) the use of (data level) mapping tables to infer new metadata as peers dynamically join the network, (2) the ability to answer queries using data in acquaintances, and (3) the ability to coordinate peers through update propagation.