diff --git a/config/prod.exs b/config/prod.exs
index 11476f9..398d584 100644
--- a/config/prod.exs
+++ b/config/prod.exs
@@ -26,8 +26,8 @@ config :poa_agent,
              identifier: "elixirNodeJSIntegration",
 
              # Authentication parameters
-             user: "rUN7afCO",
-             password: "_3IC09xfMtAW4Hr",
+             user: "AhvK0DSj",
+             password: "EkiuUkyOD6KLas8",
              token_url: "https://localhost:4003/session"
            ]
          }
@@ -41,5 +41,5 @@ config :poa_agent,
          {:eth_stats, [:rest_transfer]},
          {:eth_pending, [:rest_transfer]},
          {:eth_information, [:rest_transfer]},
-         {:system_collector, []}
+         {:system_collector, [:rest_transfer]}
        ]
diff --git a/lib/poa_agent/configuration.ex b/lib/poa_agent/configuration.ex
index bcae8de..38d3a91 100644
--- a/lib/poa_agent/configuration.ex
+++ b/lib/poa_agent/configuration.ex
@@ -24,21 +24,21 @@ defmodule POAAgent.Configuration do
     defp config(overlay, default) do
       overlay
       |> Kernel.get_in(["POAAgent", "transfers"])
-      |> Kernel.hd()
       |> merge_overlay_into_config(default)
     end
 
-    defp merge_overlay_into_config(overlay, [{id, module_name, default}]) do
-      keys = [
-        "address",
-        "identifier",
-        "secret"
-      ]
-      ^id = String.to_existing_atom(Map.fetch!(overlay, "id"))
-      restricted = Map.take(overlay, keys)
-      want = POAAgent.Configuration.to_keyword(restricted)
-      final = Keyword.merge(default, want)
-      [{id, module_name, final}]
+    defp merge_overlay_into_config(overlay, default) do
+      Enum.flat_map(default,
+        fn {id, module_name, args} ->
+          case POAAgent.Configuration.search(overlay, Atom.to_string(id)) do
+            [] ->
+              []
+            overlay_args ->
+              overlay_args = POAAgent.Configuration.to_keyword(overlay_args)
+              final = Keyword.merge(args, overlay_args)
+              [{id, module_name, final}]
+          end
+        end)
     end
   end
 
@@ -65,28 +65,35 @@ defmodule POAAgent.Configuration do
     defp config(overlay, default) do
       overlay
       |> Kernel.get_in(["POAAgent", "collectors"])
-      |> Kernel.hd()
       |> merge_overlay_into_config(default)
     end
 
-    defp merge_overlay_into_config(overlay, [{id, module_name, freq, tag, default} | rest]) do
-      keys = [
-        "url",
-        "name",
-        "contact"
-      ]
-      ^id = String.to_existing_atom(Map.fetch!(overlay, "id"))
-      restricted = Map.take(overlay, keys)
-      want = POAAgent.Configuration.to_keyword(restricted)
-      final = Keyword.merge(default, want)
-      [{id, module_name, freq, tag, final}] ++ rest
+    defp merge_overlay_into_config(overlay, default) do
+      Enum.flat_map(default,
+        fn {id, module_name, freq, tag, args} ->
+          case POAAgent.Configuration.search(overlay, Atom.to_string(id)) do
+            [] ->
+              []
+            overlay_args ->
+              overlay_args = POAAgent.Configuration.to_keyword(overlay_args)
+              final = Keyword.merge(args, overlay_args)
+              [{id, module_name, freq, tag, final}]
+          end
+        end)
     end
   end
 
+  def to_keyword(nil), do: []
   def to_keyword(x) do
     f = fn {k, v} ->
-      {String.to_existing_atom(k), v}
+      {String.to_atom(k), v}
     end
     Enum.into(x, [], f)
   end
+
+  def search(list, key) do
+    Enum.find(list, fn(map) ->
+      Map.get(map, "id") == key
+    end)
+  end
 end
diff --git a/test/poa_agent/config_overlay.json b/test/poa_agent/config_overlay.json
index 80a3c7d..2cb80af 100644
--- a/test/poa_agent/config_overlay.json
+++ b/test/poa_agent/config_overlay.json
@@ -1,6 +1,10 @@
 {
     "POAAgent":{
         "collectors":[
+            {
+                "id": "other_collector",
+                "myfield": "myvalue"
+            },
             {
                 "id": "eth_information",
                 "url": "http://localhost:8546",
@@ -9,11 +13,17 @@
             }
         ],
         "transfers":[
+            {
+                "id": "transfer1",
+                "somefield": "somevalue",
+                "somefield2": "somevalue2"
+            },
             {
                 "id": "rest_transfer",
                 "address": "http://localhost:4003",
                 "identifier": "NewIdentifier",
-                "secret": "newsecret"
+                "user": "user1",
+                "password": "password1"
             }
         ]
     }
diff --git a/test/poa_agent/configuration_test.exs b/test/poa_agent/configuration_test.exs
index 3349cdd..37863b2 100644
--- a/test/poa_agent/configuration_test.exs
+++ b/test/poa_agent/configuration_test.exs
@@ -6,11 +6,13 @@ defmodule POAAgent.ConfigurationTest do
 
     transfers = [
        {:rest_transfer, POAAgent.Plugins.Transfers.HTTP.REST, [
-           address: "http://localhost:4002",
-           identifier: "elixirNodeJSIntegration",
-           secret: "mysecret"
-         ]
-       }
+             address: "http://localhost:4002",
+             identifier: "elixirNodeJSIntegration",
+             user: "AhvK0DSj",
+             password: "EkiuUkyOD6KLas8",
+             token_url: "https://localhost:4003/session"
+           ]
+         }
      ]
 
     :ok = Application.put_env(:poa_agent, :transfers, transfers)
@@ -20,13 +22,59 @@ defmodule POAAgent.ConfigurationTest do
     # those values are in the test/poa_agent/config_overlay.json file
     new_address = "http://localhost:4003"
     new_identifier = "NewIdentifier"
-    new_secret = "newsecret"
+    new_user = "user1"
+    new_password = "password1"
 
     [{:rest_transfer, POAAgent.Plugins.Transfers.HTTP.REST, new_args}] = POAAgent.Configuration.Transfers.config()
 
     assert new_address == new_args[:address]
     assert new_identifier == new_args[:identifier]
-    assert new_secret == new_args[:secret]
+    assert new_user == new_args[:user]
+    assert new_password == new_args[:password]
+    assert "https://localhost:4003/session" == new_args[:token_url]
+
+    # putting back the original value
+    :ok = Application.put_env(:poa_agent, :transfers, original_transfers)
+
+    assert original_transfers == Application.fetch_env!(:poa_agent, :transfers)
+  end
+
+  test "Transfers overlay doesn't exist in default" do
+    original_transfers = Application.fetch_env!(:poa_agent, :transfers)
+
+    transfers = [
+       {:rest_transfer2, POAAgent.Plugins.Transfers.HTTP.REST, [
+             address: "http://localhost:4002",
+             identifier: "elixirNodeJSIntegration",
+             user: "AhvK0DSj",
+             password: "EkiuUkyOD6KLas8",
+             token_url: "https://localhost:4003/session"
+           ]
+         }
+     ]
+
+    :ok = Application.put_env(:poa_agent, :transfers, transfers)
+
+    assert transfers == Application.fetch_env!(:poa_agent, :transfers)
+
+    assert transfers == POAAgent.Configuration.Transfers.config()
+
+    # putting back the original value
+    :ok = Application.put_env(:poa_agent, :transfers, original_transfers)
+
+    assert original_transfers == Application.fetch_env!(:poa_agent, :transfers)
+  end
+
+  test "Transfers overlay, default is an empty list" do
+    original_transfers = Application.fetch_env!(:poa_agent, :transfers)
+
+    transfers = []
+
+    :ok = Application.put_env(:poa_agent, :transfers, transfers)
+
+    assert transfers == Application.fetch_env!(:poa_agent, :transfers)
+
+    assert transfers == POAAgent.Configuration.Transfers.config()
 
     # putting back the original value
     :ok = Application.put_env(:poa_agent, :transfers, original_transfers)
@@ -50,7 +98,7 @@ defmodule POAAgent.ConfigurationTest do
 
     assert collectors == Application.fetch_env!(:poa_agent, :collectors)
 
-    # # those values are in the test/poa_agent/config_overlay.json file
+    # those values are in the test/poa_agent/config_overlay.json file
     new_url = "http://localhost:8546"
     new_name = "NewNodeName"
     new_contact = "mynewemail@gmail.com"
@@ -89,7 +137,7 @@ defmodule POAAgent.ConfigurationTest do
 
     assert collectors == Application.fetch_env!(:poa_agent, :collectors)
 
-    # # those values are in the test/poa_agent/config_overlay.json file
+    # those values are in the test/poa_agent/config_overlay.json file
     new_url = "http://localhost:8546"
     new_name = "NewNodeName"
     new_contact = "mynewemail@gmail.com"
@@ -105,4 +153,59 @@ defmodule POAAgent.ConfigurationTest do
 
     assert original_collectors == Application.fetch_env!(:poa_agent, :collectors)
   end
+
+  test "test coverage for collectors" do
+    original_collectors = Application.fetch_env!(:poa_agent, :collectors)
+    original_config_overlay = Application.fetch_env!(:poa_agent, :config_overlay)
+
+    collectors = [
+       {:eth_information, POAAgent.Plugins.Collectors.Eth.Information, 60_000, :eth_information, [
+          url: "http://localhost:8545",
+          name: "Elixir-NodeJS-Integration",
+          contact: "myemail@gmail.com"
+          ]
+       },
+       {:other_collector, POAAgent.Plugins.Collectors.Eth.Information, 60_000, :eth_information, [
+          url: "http://localhost:8545",
+          name: "Elixir-NodeJS-Integration",
+          contact: "myemail@gmail.com"
+          ]
+       }
+     ]
+
+    :ok = Application.put_env(:poa_agent, :collectors, collectors)
+
+    assert collectors == Application.fetch_env!(:poa_agent, :collectors)
+
+    :ok = Application.delete_env(:poa_agent, :config_overlay)
+
+    assert collectors == POAAgent.Configuration.Collectors.config()
+
+    # putting back the original value
+    :ok = Application.put_env(:poa_agent, :collectors, original_collectors)
+    :ok = Application.put_env(:poa_agent, :config_overlay, original_config_overlay)
+
+    assert original_collectors == Application.fetch_env!(:poa_agent, :collectors)
+  end
+
+  test "test coverage for transfers" do
+    original_transfers = Application.fetch_env!(:poa_agent, :transfers)
+    original_config_overlay = Application.fetch_env!(:poa_agent, :config_overlay)
+
+    transfers = []
+
+    :ok = Application.put_env(:poa_agent, :transfers, transfers)
+
+    assert transfers == Application.fetch_env!(:poa_agent, :transfers)
+
+    :ok = Application.delete_env(:poa_agent, :config_overlay)
+
+    assert transfers == POAAgent.Configuration.Transfers.config()
+
+    # putting back the original value
+    :ok = Application.put_env(:poa_agent, :transfers, original_transfers)
+
+    assert original_transfers == Application.fetch_env!(:poa_agent, :transfers)
+    :ok = Application.put_env(:poa_agent, :config_overlay, original_config_overlay)
+  end
 end