diff --git a/src/main/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMerger.java b/src/main/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMerger.java
index c494c5797a..17f7fb4b7e 100644
--- a/src/main/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMerger.java
+++ b/src/main/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMerger.java
@@ -3,12 +3,20 @@
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.stereotype.Component;
 
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+
 @Component
 public class DraftCaseJsonMerger {
 
+    private static final Set<String> REPLACE_FIELDS = Set.of("address");
+
+
     private final ObjectMapper objectMapper;
 
     public DraftCaseJsonMerger(@Qualifier("draftCaseDataObjectMapper") ObjectMapper objectMapper) {
@@ -25,6 +33,9 @@ public DraftCaseJsonMerger(@Qualifier("draftCaseDataObjectMapper") ObjectMapper
      */
     public String mergeJson(String baseJson, String patchJson) throws JsonProcessingException {
         JsonNode base = objectMapper.readValue(baseJson, JsonNode.class);
+        JsonNode patch = objectMapper.readValue(patchJson, JsonNode.class);
+
+        applyReplaceRulesRecursively(base, patch);
 
         JsonNode merged = objectMapper.readerForUpdating(base)
             .readValue(patchJson);
@@ -32,4 +43,35 @@ public String mergeJson(String baseJson, String patchJson) throws JsonProcessing
         return objectMapper.writeValueAsString(merged);
     }
 
+    /**
+     * Clears fields in the base JSON where the patch contains an address object.
+     * Fully replaces the old fields rather than merging individual fields.
+     */
+    private void applyReplaceRulesRecursively(JsonNode base, JsonNode patch) {
+        if (!patch.isObject() || !base.isObject()) {
+            return;
+        }
+
+        Iterator<Map.Entry<String, JsonNode>> fields = patch.properties().iterator();
+        while (fields.hasNext()) {
+            Map.Entry<String, JsonNode> field = fields.next();
+            String fieldName = field.getKey();
+            JsonNode patchChild = field.getValue();
+
+            if (base.has(fieldName)) {
+                JsonNode baseChild = base.get(fieldName);
+
+                if (REPLACE_FIELDS.contains(fieldName.toLowerCase())
+                    && patchChild.isObject()
+                    && base instanceof ObjectNode) {
+
+                    ((ObjectNode) base).set(fieldName, objectMapper.createObjectNode());
+
+                } else {
+                    applyReplaceRulesRecursively(baseChild, patchChild);
+                }
+            }
+        }
+    }
+
 }
diff --git a/src/test/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMergerTest.java b/src/test/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMergerTest.java
index be649c4cec..9305999c83 100644
--- a/src/test/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMergerTest.java
+++ b/src/test/java/uk/gov/hmcts/reform/pcs/ccd/service/DraftCaseJsonMergerTest.java
@@ -14,10 +14,13 @@
 import uk.gov.hmcts.reform.pcs.ccd.type.DynamicStringListElement;
 import uk.gov.hmcts.reform.pcs.config.JacksonConfiguration;
 
+import com.fasterxml.jackson.databind.JsonNode;
+
 import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+
 class DraftCaseJsonMergerTest {
 
     private ObjectMapper objectMapper;
@@ -114,4 +117,82 @@ private DynamicStringListElement createListElement(ClaimantType value) {
         return DynamicStringListElement.builder().code(value.name()).label(value.getLabel()).build();
     }
 
+    @Test
+    void shouldClearAddressFieldsWhenPatchContainsAddress() throws Exception {
+        //Given
+        String baseJson = """
+        {
+          "party": {
+            "address": {
+              "AddressLine1": "Old Line 1",
+              "AddressLine2": "Old Line 2",
+              "AddressLine3": "Old Line 3",
+              "PostTown": "Old Town",
+              "County": "Old County",
+              "PostCode": "OLD123",
+              "Country": "Old Country"
+            }
+          }
+        }
+            """;
+
+        String patchJson = """
+            {
+              "party": {
+                "address": {
+                  "AddressLine1": "New Line 1"
+                }
+              }
+            }
+            """;
+
+        // When
+        String mergedJson = underTest.mergeJson(baseJson, patchJson);
+        JsonNode merged = objectMapper.readTree(mergedJson);
+        JsonNode address = merged.at("/party/address");
+
+        // Then: new field present
+        assertThat(address.get("AddressLine1").asText()).isEqualTo("New Line 1");
+
+        // All old fields removed
+        assertThat(address.has("AddressLine2")).isFalse();
+        assertThat(address.has("AddressLine3")).isFalse();
+        assertThat(address.has("PostTown")).isFalse();
+        assertThat(address.has("County")).isFalse();
+        assertThat(address.has("PostCode")).isFalse();
+        assertThat(address.has("Country")).isFalse();
+    }
+
+    @Test
+    void shouldNotClearAddressIfPatchDoesNotContainAddress() throws Exception {
+        //Given
+        String baseJson = """
+        {
+          "party": {
+            "address": {
+              "AddressLine1": "Line 1",
+              "PostCode": "ABC123"
+            }
+          }
+        }
+            """;
+
+        String patchJson = """
+            {
+              "party": {
+                "name": "John"
+              }
+            }
+            """;
+
+        // When
+        String mergedJson = underTest.mergeJson(baseJson, patchJson);
+        JsonNode merged = objectMapper.readTree(mergedJson);
+        JsonNode address = merged.at("/party/address");
+
+        // Then: address untouched
+        assertThat(address.get("AddressLine1").asText()).isEqualTo("Line 1");
+        assertThat(address.get("PostCode").asText()).isEqualTo("ABC123");
+    }
+
 }