One of the most misunderstood feature in Virtual Machine Manager 2012 R2 is the cross migration of Virtual Machines from one Hyper-V Failover Cluster to another Hyper-V Failover Cluster or from one Standalone Hyper-V Host to a Hyper-V Failover Cluster.
Cross migration capability is provided by Hyper-V and the Failover Clustering feature of the Windows Server Operating System. Cross migration isn’t a feature of Virtual Machine Manager 2012 R2. It would not be wrong if we define Virtual Machine Manager as a User Interface to provide a centralized management overview for your virtualized environment.
VMM in reality uses native Hyper-V and Failover Clustering related Powershell Commands in the background if you do anything over the VMM Console UI.
The most wrong thought is that the addition of a Cluster or Standalone Hyper-V Host to a VMM 2012 R2 will automatically allow the cross migration of VM’s between Clusters or Standalone Hyper-V Hosts.
Prior to be able to cross migrate VM’s, Hyper-V and Failover Cluster must be configured. As soon as the cross migration of VM’s are possible over the Failover Cluster or over the Hyper-V Manager it will also possible over the VMM Console UI.
The addition of a Cluster or Standalone Hyper-V Host to VMM doesn’t automatically allow the cross migration of VM’s nor VMM is a required Software to cross migrate VM’s.
Some useful links regarding cross migration for your reference :
How to Move Highly Available (Clustered) VMs to Windows Server 2012 with the Cluster Migration Wizard
Migration of Highly Available Virtual Machines Using the Migrate a Cluster Wizard
Migration Between Two Multi-Node Clusters
Migrating Clustered Services and Applications to Windows Server 2012
Hope it helps !