How to migrate hosts from one vCenter to another with vDS?

Hello,

I have 3 hosts that is currently on vCenter 5 and I would like to move them into my newly built vCenter 5.1.  Normally, this would be an easy task but with vDS's involve I am a bit confuse of how to do the migration without loosing the vDS's and setting.  I don't want to have to rebuild the vDS's in the newly built vCenter 5.1

What are the steps?  Any help would be appreciated.

Thanks,