Disk2vhd : Single vhdx for multiple disks - What now?

I've used disk2vhd in the past with no issues.

I downloaded the latest version (v1.53) and ran it on Server 2008, ticked the c: drive and d: drives and enabled vhdx format.  When it completed it didn't create a separate files for each volume, it created a single vhdx file that includes both volumes.

When you mount the resulting vhx file on server 2012r2 it shows three drives in explorer, one is the container vhdx which explorer thinks need formatting and then two further drives corresponding to my c: and d: volumes.

Basically I want to attach the c and d volumes to a vm in hyper-v manager but I don't know how do go about it.

Any help would be much appreciated.

Thanks