If the folder is on a device that is compatible with libraries (such as an external hard drive), it can be included. However, the content of the folder will only be available when the device is connected to your computer.
If the folder is on a computer that is part of your homegroup, it can be included. For more information, search Windows Help and Support for “add computers to a homegroup.”
If the folder is on a network device that is not part of your homegroup, it can be included as long as the content of the folder is indexed. If the folder is already indexed on the device where it is stored, you should be able to include it directly in the library.
If the network folder is not indexed, an easy way to index it is to make the folder available offline. This will create offline versions of the files in the folder, and add these files to the index on your computer. Once you make a folder available offline, you can include it in a library.
When you make a network folder available offline, copies of all the files in that folder will be stored on your computer’s hard disk. Take this into consideration if the network folder contains a large number of files.
To make a folder available offline
While connected to the network, locate the network folder that you want to make available offline.
Right-click the folder, and then click Always available offline.
The Always available offline command
If you don’t see the Always available offline command, you might be using an edition of Windows 7 that doesn’t support offline files.