Get-NaVol | Where {$_.CloneParent -ne $null -and $_.CloneParent[0].ParentVolumeName -eq "<parent volume name>"}
Let say my <patent volume name> is Win2K8R2SP1_MASTER, Executing command:
Get-NaVol | Where {$_.CloneParent -ne $null -and $_.CloneParent[0].ParentVolumeName -eq "Win2K8R2SP1_MASTER"}
gives me list of all FlexClones created from Win2K8R2SP1_MASTER volume. Also using $_.CloneParent[0].ParentSnapshotName in Where statement can add additional filtering for specific snapshot used for FlexClone.
If you want to display list of Flex Clones with their Parent Volume and Snapshot:
$FlexClones = Get-NaVol | Where {$_.CloneParent -ne $null -and $_.CloneParent[0].ParentVolumeName -eq "<parent volume name>"}
ForEach ($FlexClone in FlexClones)
{
$FlexClone.Name
$FlexClone.CloneParent[0].ParentVolumeName
$FlexClone.CloneParent[0].ParentSnapshotName
}