R-GMA is a relational implementation of the GGF's Grid Monitoring Architecture (GMA). In some respects it can be seen as a virtual database (VDB), supporting the publishing and retrieval of time-stamped tuples. The scope of an R-GMA installation is defined by its schema and registry. The schema holds the table definitions and, in future, the authorization rules. The registry holds a list of the available producers and consumers. At present, while it is possible to have multiple installations, a user can only use one at a time and hence cannot access tables in another installation. We plan to introduce multiple VDBs, where each VDB is defined by its own registry and schema. In this paper we explain the basic idea of R-GMA, why we need multiple VDBs to support multiple VOs, and how we will implement them. We also discuss the possible need to create some VDBs not related to end-user VOs. We also explain why we do not plan to provide a catalogue of VDBs as a part of R-GMA.