Bit of clarrification / insight:
vSwitch0
Management
vmk1:192.168.200.102
DG is 192.168.200.250.
vSwitch6
iSCSI2
vmk3: 192.168.30.162
iSCSI
vmk2: 192.168.30.161
If I try to add a gateway to the two new port groups above I get taken to the UI for the VMK1 port group resulting in modifying the management gateway.