Episciences is a platform to publish diamond open access overlay journals. The ambition is to provide the scientific communities with the technical means to produce high quality journals, at an efficient cost, compliant by design with FAIR principles. The process relies on open repositories (arXiv ; Zenodo ; HAL ; CWI). The presentation will explain how Episciences overcame the limitations of its previous metadata ingestion model and leveraged the services of open scientific infrastructures. In this regard, we have also implemented the COAR notification protocol and the "Signposting the Scholarly Web" approach that allow us to efficiently exchange information with compatible open repositories like HAL. This allows us to offer them enriched metadata in turn. We will conclude by explaining why our metadata enrichment methodology should ideally evolve in the future to be also based on the Notify/Linked Data Notification approach, as soon as other COAR Notify compatible platforms or repositories appear.