A remote vCenter Server can be added as one of the targets. The pairing is mandatory when both the sites are managed by different vCenter Servers. This is because the VRM Server registered to the protected site vCenter can only see vSphere Replication (VR) Servers that are registered to it. You can deploy multiple VR Servers at either of the sites, but pairing can only be used if they are registered to its local VRM server. The pairing will not be possible if the vCenter Server managing the remote site does not have a VRMS registered to it.
When adding a target site, you are prompted to specify the address (FQDN/IP) and connection credentials of the vCenter Server managing the target site. Most environments use separate accounts for connections between different vSphere components. The separate account can also be a service account corresponding to that component. In that case, you can use the service account corresponding to the vCenter Server that you are...