Add a database label field to an entity,and an option to show that label in the entity naming label.
i.e. displayed in the diagram as either databasename.schema.table or databasename schema.table (without dot between db and sch name).
Or alternatively integrate support for cross db modelling i.e. have a new top layer in the explorer starting with a list of databases. An then switch options to show or not show the database and schema parts of the entity naming etc.
Customer support service by UserEcho