As lexical databases have proliferated in multiple formats, there has been a growing concern over the reusability of lexical resources. The interchange and integration of data, as well as the development of common software is increasingly important to avoid duplications of effort and enable the development of large-scale databases of linguistic information. A unified approach for the development of tools to create and manage lexical databases is necessary. Their structure must follow some patterns based on some clearly delimited abstraction levels and the implementation must be controlled by sound and well-founded software engineering methods. Relational database technology is suitable for data support and to attain a greater flexibility, reusability and expandability. With such a methodology we have developed tools for the creation and management of monolingual dictionaries based on a Directed Acyclic Graph shaped conceptual taxonomy with a single relation where a category can have more than one parent. This is a new step in the way to develop tools for managing well structured lexical databases and with multiple semantic relations