The Related Drives wizard panel appears only if you initially selected a drive with applications configured to use one or more of the drives that are listed in this panel. Such applications include boot configuration databases (as found in Windows Vista and Windows 7) that are on a separate drive from where the operating system is installed.
If you want to backup an attached Microsoft Virtual Hard Disk (VHD), you must create a separate backup job for the host drive and for the attached VHD. For example, if the VHD host is on the C: drive and the attached VHD is the D: drive, you must create a backup job for C: and a backup job for D:. Also, you cannot backup an attached VHD that is nested within another attached VHD.
See About backing up Microsoft virtual hard disks.
If you use Microsoft’s BitLocker Drive Encryption to encrypt the data on a data drive (any drive that does not have the operating system installed on it), be aware that Norton Ghost does not work with locked data drives. Instead, you must unlock the bitlocked drive before you can backup it up.
Generally, you should accept the preselected option Add all related drives (recommended). Doing so can help you with a successful recovery, should you ever need to perform a restore in the future. If you deselect certain related drives you may experience an incomplete recovery or an unsuccessful recovery.