diff --git a/contracts/src/v0.8/dev/automation/upkeeps/MercuryRegistry.sol b/contracts/src/v0.8/dev/automation/upkeeps/MercuryRegistry.sol
index 0b665e72c79..de7353e5cb1 100644
--- a/contracts/src/v0.8/dev/automation/upkeeps/MercuryRegistry.sol
+++ b/contracts/src/v0.8/dev/automation/upkeeps/MercuryRegistry.sol
@@ -28,6 +28,9 @@ import "../../../ChainSpecificUtil.sol";
 |   - Optimize gas consumption.                                                                                       |
 -+---------------------------------------------------------------------------------------------------------------------*/
 contract MercuryRegistry is AutomationCompatibleInterface, FeedLookupCompatibleInterface {
+  error DuplicateFeed(string feedId);
+  error FeedNotActive(string feedId);
+
   // Feed object used for storing feed data.
   // not included but contained in reports:
   // - blocknumberUpperBound
@@ -41,6 +44,7 @@ contract MercuryRegistry is AutomationCompatibleInterface, FeedLookupCompatibleI
     int192 ask; // the current ask price of the feed
     string feedName; // the name of the feed
     string feedId; // the id of the feed (hex encoded)
+    bool active; // true if the feed is being actively updated, otherwise false
   }
 
   // Report object obtained from off-chain Mercury server.
@@ -78,24 +82,49 @@ contract MercuryRegistry is AutomationCompatibleInterface, FeedLookupCompatibleI
   ) {
     i_verifier = IVerifierProxy(verifier);
 
-    // Ensure correctly formatted constructor arguments.
-    require(feedIds.length == feedNames.length, "incorrect constructor args");
-
     // Store desired deviation threshold and staleness seconds.
     s_deviationPercentagePPM = deviationPercentagePPM;
     s_stalenessSeconds = stalenessSeconds;
 
     // Store desired feeds.
+    setFeeds(feedIds, feedNames);
+  }
+
+  function setFeeds(string[] memory feedIds, string[] memory feedNames) public {
+    // Ensure correctly formatted constructor arguments.
+    require(feedIds.length == feedNames.length, "incorrectly formatted feeds");
+
+    // Clear prior feeds.
+    for (uint256 i = 0; i < s_feeds.length; i++) {
+      s_feedMapping[s_feeds[i]].active = false;
+    }
+
+    // Assign new feeds.
+    for (uint256 i = 0; i < feedIds.length; i++) {
+      string memory feedId = feedIds[i];
+      if (s_feedMapping[feedId].active) {
+        revert DuplicateFeed(feedId);
+      }
+
+      s_feedMapping[feedId].feedName = feedNames[i];
+      s_feedMapping[feedId].feedId = feedId;
+      s_feedMapping[feedId].active = true;
+    }
     s_feeds = feedIds;
+  }
+
+  function addFeeds(string[] memory feedIds, string[] memory feedNames) external {
     for (uint256 i = 0; i < feedIds.length; i++) {
-      s_feedMapping[s_feeds[i]] = Feed({
-        feedName: feedNames[i],
-        feedId: feedIds[i],
-        price: 0,
-        bid: 0,
-        ask: 0,
-        observationsTimestamp: 0
-      });
+      string memory feedId = feedIds[i];
+      if (s_feedMapping[feedId].active) {
+        revert DuplicateFeed(feedId);
+      }
+
+      s_feedMapping[feedId].feedName = feedNames[i];
+      s_feedMapping[feedId].feedId = feedId;
+      s_feedMapping[feedId].active = true;
+
+      s_feeds.push(feedId);
     }
   }
 
diff --git a/contracts/test/v0.8/foundry/automation/MercuryRegistry.t.sol b/contracts/test/v0.8/foundry/automation/MercuryRegistry.t.sol
index 5d6d4a8ac0d..3ef311b22bc 100644
--- a/contracts/test/v0.8/foundry/automation/MercuryRegistry.t.sol
+++ b/contracts/test/v0.8/foundry/automation/MercuryRegistry.t.sol
@@ -48,14 +48,30 @@ contract MercuryRegistryTest is Test {
     vm.selectFork(vm.createFork("https://arbitrum-goerli.publicnode.com"));
     vm.rollFork(BLOCK_NUMBER);
 
-    // Create Mercury Registry.
+    // Use a BTC feed and ETH feed.
     feedIds = new string[](2);
     feedIds[0] = s_BTCUSDFeedId;
     feedIds[1] = s_ETHUSDFeedId;
-    string[] memory feedNames = new string[](2);
-    feedNames[0] = "BTC/USD";
-    feedNames[1] = "ETH/USD";
-    s_testRegistry = new MercuryRegistry(feedIds, feedNames, VERIFIER, DEVIATION_THRESHOLD, STALENESS_SECONDS);
+
+    // Initialize with BTC feed.
+    string[] memory initialFeedIds = new string[](1);
+    initialFeedIds[0] = feedIds[0];
+    string[] memory initialFeedNames = new string[](1);
+    initialFeedNames[0] = "BTC/USD";
+    s_testRegistry = new MercuryRegistry(
+      initialFeedIds,
+      initialFeedNames,
+      VERIFIER,
+      DEVIATION_THRESHOLD,
+      STALENESS_SECONDS
+    );
+
+    // Add ETH feed.
+    string[] memory addedFeedIds = new string[](1);
+    addedFeedIds[0] = feedIds[1];
+    string[] memory addedFeedNames = new string[](1);
+    addedFeedNames[0] = "ETH/USD";
+    s_testRegistry.addFeeds(addedFeedIds, addedFeedNames);
   }
 
   function testMercuryRegistry() public {
@@ -92,7 +108,8 @@ contract MercuryRegistryTest is Test {
       int192 bid,
       int192 ask,
       string memory feedName,
-      string memory localFeedId
+      string memory localFeedId,
+      bool active
     ) = s_testRegistry.s_feedMapping(s_BTCUSDFeedId);
     assertEq(observationsTimestamp, 1692732568); // Tuesday, August 22, 2023 7:29:28 PM
     assertEq(bid, 2585674416498); //   $25,856.74416498
@@ -100,6 +117,7 @@ contract MercuryRegistryTest is Test {
     assertEq(ask, 2585747836943); //   $25,857.47836943
     assertEq(feedName, "BTC/USD");
     assertEq(localFeedId, s_BTCUSDFeedId);
+    assertEq(active, true);
 
     // Obtain mercury report off-chain (for August 23 BTC/USD price & ETH/USD price)
     values = new bytes[](2);
@@ -185,7 +203,8 @@ contract MercuryRegistryTest is Test {
       int192 bid,
       int192 ask,
       string memory feedName,
-      string memory localFeedId
+      string memory localFeedId,
+      bool active
     ) = s_testRegistry.s_feedMapping(s_BTCUSDFeedId);
     assertEq(observationsTimestamp, 1692732568); // Tuesday, August 22, 2023 7:29:28 PM
     assertEq(bid, 2585674416498); //   $25,856.74416498
@@ -193,6 +212,7 @@ contract MercuryRegistryTest is Test {
     assertEq(ask, 2585747836943); //   $25,857.47836943
     assertEq(feedName, "BTC/USD");
     assertEq(localFeedId, s_BTCUSDFeedId);
+    assertEq(active, true);
 
     // Obtain mercury report off-chain (for August 23 BTC/USD price & ETH/USD price)
     values = new bytes[](2);