Trying to add second DC to vCenter instance.

All:

I am positive that there is a way to add a second "Datacenter" to an instance of vCenter, when the second DC is managed by its own vCenter server. Our current situation is that we have two physically seperate datacenters, both running vSphere 5.0. We would like it so that say for example, my vCenter instance can see the other DC and it's resources, but that DC stay managed by the instance of vCenter that is local to it, not mine.

Is this possible? Am I overlooking anything here? I have no issues creating the DC object, but when going to add the host's to that DC, it alerts me that they are currently being managed by another instance of vCenter...?

Thank you for the help in advance.

Thank You.