Connection ESRI Geodatabase Map connections

I have several ESRI File geodatabases (one GDB per country) and want to use them as graphical sources.

Question 1: In the GSA I can obviously only specify one FGB as data source, right? How Is it possible to register and use more than one GDB?

Question 2: I want to update the GDB Connection created in the past in a DGN, because new data has been added in the GDB. However, the connection is not displayed. How can I reactivate a seemingly still existing connection and make it visible?
As soon as I want to recreate the GDB Connection in the Map Connections Tool I get the error message: "Error Opening GDB Storage: The requested file geodatabase is already open and in use.