A web-based system, method and program product are provided for adding content to a content object (e.g., a custom compilation or prepublished work) stored in a data repository as a group of hierarchically related content entities. Each content entity is also stored as a row in a digital library index class as a collection of attributes and references to related content entities and containers. As the user selects desired objects for inclusion in a content object, the system arranges the objects hierarchically, e.g., into volumes, chapters and sections according to the order specified by the user. Furthermore, prerequisite checking, wherein some entities are associated, e.g., by a set of rules, with content objects that are prerequisites to that objects, and wherein selection by the user of an entity having prerequisites causes automatic inclusion of all associated prerequisite objects in the final compilation.