A mediation system for a converged network system for an xSP (i.e., any service provider of Information Technology (IT)/business services) is readily interactively configured by a user (e.g., an xSP) to correlate and aggregate usage data from a number of collection points for billing-related purposes. Usage data that includes a source record and one or more related records are matched, assembled upon satisfying assembly criteria (e.g., time-base, expression-based, volume-based), and returned in accordance with an assembly specification (e.g., one to one, one to many, many to many).