VHD files appear just like physical disks in Hyper-V VHD Explorer. When a VHD has been attached (that is, made available to the system for use), you can access the list of Volumes within it.
To explore the volumes on the attached VHD file, follow the steps below.
2. Select an attached VHD in the "Attached VHDs" pane.
The Volumes of the selected VHD are displayed in the right "Volumes in..." pane.
See Managing VHD Volumes.