The way I do this is:
Create a new VM without a disk.
When the VM is created, go to hardware.
Select Add disk and select the correct storage location and disk file.
Now you need to set the added disk as the boot disk in the VM settings.
Create a new VM without a disk.
When the VM is created, go to hardware.
Select Add disk and select the correct storage location and disk file.
Now you need to set the added disk as the boot disk in the VM settings.