I'm recently studying about how to enable a workload management cluster and I saw this topology: 
my questions are, for the vSphere version not older than 7 and VCF version not older than 4.0, should the management network of the 3 supervisor VMs always use virtual switch portgroup of VLAN network (which is reachable from vCenter/NSX-T)?
is it doable to use nsx-t overlay network as the management for supervisor VMs or maybe it would be too complicated?
is one of the supervisor VMs' management IP act as HA or load-balancing purpose?