In this paper we describe a way to enhance existing digital library documents by adding links without modifying the stored documents themselves. We show how to use a combination of XSLT and a host language to access a database with linking information and how to merge documents and links at run-time (a posteriori cross linking). Our approach is already used in the system OMNIS/2, which is an advanced meta system for existing digital library systems and enhances existing digital library systems or retrieval systems by additional storing and indexing of user-defined multimedia documents, automatic and personal linking concepts, annotations, filtering and personalization.