Yes, you can if you need to. Few things you need to remember. Site VX has to have APs at level 1 mint link and NOC VX adopts site VX at level 2 mint link. That's a MUST.
Then you need to bump up mint DIS priority and mint control priority for NOC VX under device. You can see current mint config by doing "show mint config" on each one. THey will match. If you want to have one VX manage several site VXs - you NOC VX mint config needs to have higher mint priority and control priority and be router while your site VX controllers need to be mint leafs (you can see this by doing "show mint info").
To adjust mint dis priority and control priority - under device of NOC VX:
(config-device)#mint ?
control-priority MiNT control priority
dis priority-adjustment Adjustment added to base priority
Alona