We can't tell from the screenshot since each file reference can actually contain multiple lines and some of those may be the correct ones too.
The correct format is the one for #3 with just the "file:" prefix
Seperations 3 will open up the file Seperations that is in the same folder/server as the primary file.
I deleted all but the one that was file:Separation
It broke a few things that were somehow point at the other ones but I getting thru most of that pretty easy
Once upon a time, direct access to and management of external data source info was not possible in FileMaker. The application managed the links internally and we had to live with whatever external data source entries thus produced. However, FileMaker was apparently listening when we complained about the problems that we were encountering due to the inability to control these settings and they introduced this tool in one of the new version releases.
When I converted a copy that originated from those days to FMP v 10 and opened up manage | External datasources, I found an awful mess of multiple duplicated data sources with multiple entries in most of them that makes what you have here look very clean and simple in comparison.
But I found that a Database Design Report (today, I'd use Base Elements or a similar tool), was invaluable in tracking down and updating data source references so that I could effectively clean up the external datasources to just one for each file.
It looks like it's too late now. But really, the thing to do BEFORE turning off all the others, is to find the scripts and table occurrences that point to the others; and point them all to ONE data source. THEN delete all the alternate data sources.