Copy VM Image (OS + Data disks) to new subscription

I have a standalone VM image for BI demos (DC+Sharepoint+SQL). I can spin up a new VM from the image for new clients etc. I followed a technet article which creates 3 disks, the OS disk, a DC data disk, and an SQL data disk

I need to move this image into a new subscription.

What would be the process?

I understand I need to move the VHDs to the new subscription, but then how do I create the new "VM Image" object from those multiple VHDs?

the Add-AzureVMImage cmdlet doesn't have a parameter for data disks. OS disk only

A link in a previous topic on this only has info on how to create an image from a running VM.

Is that what i need to do?

copy the image VHDs from sub1 into sub2
create a dummy VM from the VHDs
create a VM Img from the dummy VM
delete dummy VM

Thanks

Jakub @ Adelaide, Australia