Adding support for replicas
diff --git a/rackspace/db/v1/instances/delegate.go b/rackspace/db/v1/instances/delegate.go
index d2e3c25..ca223eb 100644
--- a/rackspace/db/v1/instances/delegate.go
+++ b/rackspace/db/v1/instances/delegate.go
@@ -58,6 +58,8 @@
 	// - You can create new users or databases if you want, but they cannot be
 	// the same as the ones from the instance that was backed up.
 	RestorePoint string
+
+	ReplicaOf string
 }
 
 func (opts CreateOpts) ToInstanceCreateMap() (map[string]interface{}, error) {
@@ -91,6 +93,10 @@
 		instance["restorePoint"] = map[string]string{"backupRef": opts.RestorePoint}
 	}
 
+	if opts.ReplicaOf != "" {
+		instance["replica_of"] = opts.ReplicaOf
+	}
+
 	return map[string]interface{}{"instance": instance}, nil
 }