How do you allocate storage from a second drive to a VM Template?

Hello everyone, new guy here trying to get my first Hyper-V + SCVMM deployment going smoothly.

So what I have running is:

Hyper-V on Server 2012

SCVMM on Server 2008 R2

Storage machine running Server 2012, connected to SCVMM via iSCSI

We are a group of technicians that want to be able to create our own virtual machines via SCVMM (we have this part working just fine!).  We have templates for our VM's for Server 2008, 2012, Win 7, etc with their VHDx files created directly on the Hyper-V server.  What I WANT to do it allow the VHDx to be created as it is, but when the VM is spawned I want it to have a second drive that stores to the "Storage Machine".

I have no idea if this is something that is possible through System Center or Hyper-V.  I have been researching for 3 days but have found no solution.  I look to the experts for help.

Thanks!!!

Anthony