I think I know the answer but here goes..
I hope this is the answer you suspected will be given:
On a mac you would have to manipulate the plist file in ~/Library/Preferences/com.filemaker.client.advanced12.plist,
your file will be called differently, it depends on the version of FileMaker installed. You can use AppleScript or bash script triggered by FileMaker to load/change values in
<plist version="1.0"> <dict> <key>:00</key> <string>filemac:/Macintosh HD/Users/nicolai/Desktop/Sudoku.fmp12</string> </dict> </plist>
<key> will denote the position in Favourites list. String should provide the filepath in the filemaker format
It is a bit trickier on Windows. The favourites are stored somewhere in registry HKEY_CURRENT_USER\Software\FileMaker and is called FavHostInfo. You can manipulate registry entries with VBS from FileMaker, just have to be extra careful as potentially you can cripple a computer with a corrupted registry.
Sorry, if you already knew that and someone might post a better way.
lol, no, the answer I thought would be - "No you cant"
However it seems possible after all so once again thanyou for your valued input..
Sorry to disappoint you.