The lack of an ontology integrating Digital Twins (DTs) into the Metaverse presents a fundamental challenge for synchronising physical and digital worlds. This study proposes the development of a specific ontology to address this very gap. To achieve this, two methodological approaches are employed: MDCP modelling and the OApIS process, allowing a comparison between a more rigid structure and a dynamic, adaptive approach. The expected outcomes include the creation of a flexible, scalable, and interoperable ontology capable of efficiently representing DTs. The study concludes that robust ontological frameworks are essential for enhancing DT-Metaverse interactions, contributing to more immersive, secure, and predictive experiences.