@Koen I will leave this in your capable hands. I see I miss-read the question. :)
Ramin
To pin a folder to the “Open” screen, run Excel > Go to file > Open > click “Computer” from open menu.
Move your mouse over a folder in the list of “Recent Folders” on the right side of the “Open” screen. Click the sideways push pin icon to pin the folder to the “Open” screen.
NOTE: If the folder you want to pin is not in the “Recent Folders” list, you can add the folder the the list by opening a document in the desired folder. To do so, click “Browse.”
On the “Open” dialog box, navigate to the folder you want to pin and select a file in the folder. Click “Open.”
Click the “File” tab again and click “Open” to go to the “Open” screen again. The “Current Folder” displays at the top of the “Computer” list, if you just opened a file in the folder. Below the “Current Folder” is the list of “Recent Folders” with the pinned folder at the top with a line below the pinned folder.
You can pin additional files and folders as well and they will all be displayed at the top of the “Recent Documents” list or “Recent Folders” list.