Both for the purposes of displaying and managing the replication topology we need a way to get a data structure that contains the full list of replicas and their agreements.

When deleting a replica we need to make sure we aren't orphaning one or more. One example is A - B - C - D - E, trying to remove C. We'd end up with two orphaned networks.

Having this data structure would also make it fairly easy to visually show the topology.