Using vhd from windows 2008 r2 hyper-v in windows server 2012 r2 hyper-v

I have a Desktop that runs windows server 2008 R2 with added hyper-v role. I am planning to reinstall the OS on Desktop to either Windows server 2012 or Windows 8.1 and install hyper-v role again.

But , I want to retain 3 virtual servers ( All windows 2008 R2) and reuse them when I am done building desktop with new OS.

Would the virtual machine work from older Windows 2008 hyper-v in 2012 or windows 8 . I am planning to save the vhd file then create a new virtual machine and present the exisiting vhd .

I cannot recreate the vm's that I trying to save because is there lots of configuration in the applications that is being done.

Thanks