Right now, adding multiple locked folders is not very convienient.
You cannot drag a folder onto the locked folder area, similar to how you can drag a folder to the file path area on the main window
If you press the folder icon to open the file browser and find the folders you want to add, you cannot hold down the Shift key to select and add multiple folders
After you add a locked folder and you press the folder icon to add another folder, the file browser window reverts you back to the default location (in my case ~/Movies) and not the folder you most recently added from.
Right now, adding multiple locked folders is not very convienient.