An Access database is getting to much data through forms so new copies get made. To make the old data available for searches the tables should be linked. The problem is that the menu group "EXTERNAL DATA" is not available. The reason for this seems to be that the file is in forms mode. As the many forms and interface elements in this file are available.
Another Access file does have all menu groups available, and it has the screen "All tables" open, so there seems to be a "table" mode.
So how to get "table" mode working or otherwise link Access tables? The file does have database entries, as it's size is 1,08 GB.