With the release of Windows Server 2012 we introduced a new virtual hard disk format known as VHDX. This new format provided the foundation for a number of features and performance enhancements. One such feature is the ability to independently expand differencing virtual hard disks without impacting the base or parent hard disk or any siblings. From the UI you can simply select ‘Edit Disk…’ input the path of the virtual hard disk and select expand from the options provided. Similarly you can utilize the new Resize-VHD cmdlet in PowerShell providing the path to the disk and the new size in bytes for example Resize-VHD -Path "C:\VHDs\Child.vhdx" -SizeBytes 80GB.