Welcome to the NetApp community !
From the SMVI Install and Admin Guide, under 'Adding a vCenter server':
Note: You can only connect to one vCenter Server.
You can however manage multiple data centers and data stores with a vCenter server, so I'm not sure why you're planning on multiple vCenter servers ?
I hope this response has been helpful to you.
At your service,
Eugene E. Kashpureff
ekashp@kashpureff.org
Fastlane NetApp Instructor and Independent Consultant
http://www.fastlaneus.com/ http://www.linkedin.com/in/eugenekashpureff
(P.S. I appreciate points for helpful or correct answers.)