A relationship and navigation data repository can interface with a central data model and contains templates that define relationships among data from a number of distributed heterogeneous data sources. An integration engine is coupled to the relationship and navigation data repository, and can receive a query command and determine which of the heterogeneous data sources and which of the templates the query applies to, and then calculate the desired query result, responsive to the command, based on the relevant data sources and templates. The distributed heterogeneous data sources are managed by a system and method that involves obtaining pre-existing definitional data, instantiating in-memory nodes for the data, initializing a relationship attribute and an entity attribute for each of the nodes, and then forming an updated navigation tree structure therefrom.