Using QspatiaLite plugin in QGIS I'm able to create a new database and work with it (load/edit/import/export data). But how can I add a connection to an existing database? How to add an existing database to the drop-down-menu of the available database connections?
You just use the same "New DB" button. If you mouse-over the button the tip says "(you can also load an existing one, just ignore the replace)".
It's very non-intuitive, and should be changed, but it works. When you point to an existing DB a warning pops up that the DB already exists and you must click "Replace" (despite the warning) then the existing tables load.