Windows server 2012 backup sees a HyperV child natively, no hacking/no registry key changes/no nothin'.
Do the VMs need to have the Integration Services installed? Or maybe just VMs running 2008r2 and below would need to have that installed?
Good question, let me ask. The only one I did integration service install on was the Home server. I have newer stuff on there for sure (Essentials 2012, a Win7/win8 and home server 2011) but I honestly did nothing to turn that on. It just lit up and found those children to back up.
and incremental imaging of them also works but not if the VHDs are on an REFS Volume DOH!!!