The ePO 4.6 manual covers policy sharing between registered servers:
Check page 184...
The web api provides a mechanism to import/export policies to the local file system (local to the ePO server).
With the Web API you would need to build a client that can import/export individual policies, communicate these to the remove site and then manage the import of the policy at the remote site. In this case you woulnd't need to have registered servers, but there's a LOT more heavy lifting.