How Include network folders files on Windows (2012) Server backup

Hi,

I would like to use Windows Server Backup to backup my Windows 2012 Server, all volumes (Full Server)

I would like to include in this  backup , shared network folders files that are located  on a NAS on my dominio.

In the past,  it was possible to select  network external folders files, with Windows 2003 server backup. 

Now, I have't found documentation for this argument in the Windows Backup manager documentation.

I hope my request will be clear for you.

I'm sorry for my English.

Thanks,

Maria