diff --git a/core/src/main/java/com/backblaze/b2/client/structures/B2ReplicationRule.java b/core/src/main/java/com/backblaze/b2/client/structures/B2ReplicationRule.java
index 145647554..2eb0f155a 100644
--- a/core/src/main/java/com/backblaze/b2/client/structures/B2ReplicationRule.java
+++ b/core/src/main/java/com/backblaze/b2/client/structures/B2ReplicationRule.java
@@ -53,21 +53,30 @@ public class B2ReplicationRule {
     @B2Json.required
     private final boolean isEnabled;
 
+    /**
+     * Indicates if existing files in the bucket will be replicated (if they have not already been replicated
+     * to the destination bucket this rule specifies).
+     */
+    @B2Json.optionalWithDefault(defaultValue = "false")
+    private final boolean includeExistingFiles;
+
     /**
      * Initializes a new, immutable rule.
      */
     @B2Json.constructor(params = "replicationRuleName, destinationBucketId, priority, " +
-        "fileNamePrefix, isEnabled")
+        "fileNamePrefix, isEnabled, includeExistingFiles")
     public B2ReplicationRule(String replicationRuleName,
                              String destinationBucketId,
                              int priority,
                              String fileNamePrefix,
-                             boolean isEnabled) {
+                             boolean isEnabled,
+                             boolean includeExistingFiles) {
         this.replicationRuleName = replicationRuleName;
         this.destinationBucketId = destinationBucketId;
         this.priority = priority;
         this.fileNamePrefix = fileNamePrefix;
         this.isEnabled = isEnabled;
+        this.includeExistingFiles = includeExistingFiles;
     }
 
     public String getReplicationRuleName() {
@@ -90,6 +99,10 @@ public boolean isEnabled() {
         return isEnabled;
     }
 
+    public boolean includeExistingFiles() {
+        return includeExistingFiles;
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -97,6 +110,7 @@ public boolean equals(Object o) {
         B2ReplicationRule that = (B2ReplicationRule) o;
         return priority == that.priority &&
                 isEnabled == that.isEnabled &&
+                includeExistingFiles == that.includeExistingFiles &&
                 Objects.equals(replicationRuleName, that.replicationRuleName) &&
                 Objects.equals(destinationBucketId, that.destinationBucketId) &&
                 Objects.equals(fileNamePrefix, that.fileNamePrefix);
@@ -109,7 +123,8 @@ public int hashCode() {
                 destinationBucketId,
                 priority,
                 fileNamePrefix,
-                isEnabled
+                isEnabled,
+                includeExistingFiles
         );
     }
 
@@ -121,6 +136,7 @@ public String toString() {
                 ", priority=" + priority +
                 ", fileNamePrefix='" + fileNamePrefix + '\'' +
                 ", isEnabled=" + isEnabled +
+                ", includeExistingFiles=" + includeExistingFiles +
                 '}';
     }
 }
diff --git a/core/src/test/java/com/backblaze/b2/client/B2StorageClientImplTest.java b/core/src/test/java/com/backblaze/b2/client/B2StorageClientImplTest.java
index d87926e28..6bdd148b1 100644
--- a/core/src/test/java/com/backblaze/b2/client/B2StorageClientImplTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/B2StorageClientImplTest.java
@@ -239,14 +239,16 @@ public void testCreateBucket() throws B2Exception {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 ),
                 new B2ReplicationRule(
                         "my-replication-rule-2",
                         "777011112222333344445555",
                         1,
                         "abc",
-                        true
+                        true,
+                        false
                 )
         );
         final Map<String, String> sourceToDestinationKeyMapping = new TreeMap<>();
@@ -310,10 +312,10 @@ public void testCreateBucket() throws B2Exception {
                 "sourceApplicationKeyId='123a0a1a2a3a4a50000bc614e', " +
                 "replicationRules=[B2ReplicationRule{replicationRuleName='my-replication-rule', " +
                 "destinationBucketId='000011112222333344445555', priority=3, fileNamePrefix='', " +
-                "isEnabled=false}, " +
+                "isEnabled=false, includeExistingFiles=true}, " +
                 "B2ReplicationRule{replicationRuleName='my-replication-rule-2', " +
                 "destinationBucketId='777011112222333344445555', priority=1, fileNamePrefix='abc', " +
-                "isEnabled=true}]}, " +
+                "isEnabled=true, includeExistingFiles=false}]}, " +
                 "asReplicationDestination=B2DestinationConfig{" +
                 "sourceToDestinationKeyMapping={123a0a1a2a3a4a50000bc614e=555a0a1a2a3a4a70000bc929a, " +
                 "456a0b9a8a7a6a50000fc614e=555a0a1a2a3a4a70000bc929a}}}}),v1)",
@@ -345,10 +347,10 @@ public void testCreateBucket() throws B2Exception {
                         "sourceApplicationKeyId='123a0a1a2a3a4a50000bc614e', " +
                         "replicationRules=[B2ReplicationRule{replicationRuleName='my-replication-rule', " +
                         "destinationBucketId='000011112222333344445555', priority=3, fileNamePrefix='', " +
-                        "isEnabled=false}, " +
+                        "isEnabled=false, includeExistingFiles=true}, " +
                         "B2ReplicationRule{replicationRuleName='my-replication-rule-2', " +
                         "destinationBucketId='777011112222333344445555', priority=1, fileNamePrefix='abc', " +
-                        "isEnabled=true}]}, " +
+                        "isEnabled=true, includeExistingFiles=false}]}, " +
                         "asReplicationDestination=B2DestinationConfig{" +
                         "sourceToDestinationKeyMapping={123a0a1a2a3a4a50000bc614e=555a0a1a2a3a4a70000bc929a, " +
                         "456a0b9a8a7a6a50000fc614e=555a0a1a2a3a4a70000bc929a}}}}),v1)",
diff --git a/core/src/test/java/com/backblaze/b2/client/structures/B2BucketReplicationConfigurationTest.java b/core/src/test/java/com/backblaze/b2/client/structures/B2BucketReplicationConfigurationTest.java
index 3836042b9..019459a7c 100644
--- a/core/src/test/java/com/backblaze/b2/client/structures/B2BucketReplicationConfigurationTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/structures/B2BucketReplicationConfigurationTest.java
@@ -29,6 +29,7 @@ public void testToJsonAndBack_sourceOnly() {
                 "      {\n" +
                 "        \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "        \"fileNamePrefix\": \"\",\n" +
+                "        \"includeExistingFiles\": true,\n" +
                 "        \"isEnabled\": false,\n" +
                 "        \"priority\": 3,\n" +
                 "        \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -36,6 +37,7 @@ public void testToJsonAndBack_sourceOnly() {
                 "      {\n" +
                 "        \"destinationBucketId\": \"777011112222333344445555\",\n" +
                 "        \"fileNamePrefix\": \"abc\",\n" +
+                "        \"includeExistingFiles\": false,\n" +
                 "        \"isEnabled\": true,\n" +
                 "        \"priority\": 1,\n" +
                 "        \"replicationRuleName\": \"my-replication-rule-2\"\n" +
@@ -58,7 +60,8 @@ public void testToJsonAndBack_sourceOnly() {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 )
         );
         replicationRules.add(
@@ -67,7 +70,8 @@ public void testToJsonAndBack_sourceOnly() {
                         "777011112222333344445555",
                         1,
                         "abc",
-                        true
+                        true,
+                        false
                 )
         );
         final B2BucketReplicationConfiguration defaultConfig =
@@ -129,6 +133,7 @@ public void testToJsonAndBack_sourceAndDestination() {
                 "      {\n" +
                 "        \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "        \"fileNamePrefix\": \"\",\n" +
+                "        \"includeExistingFiles\": true,\n" +
                 "        \"isEnabled\": false,\n" +
                 "        \"priority\": 3,\n" +
                 "        \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -136,6 +141,7 @@ public void testToJsonAndBack_sourceAndDestination() {
                 "      {\n" +
                 "        \"destinationBucketId\": \"777011112222333344445555\",\n" +
                 "        \"fileNamePrefix\": \"abc\",\n" +
+                "        \"includeExistingFiles\": false,\n" +
                 "        \"isEnabled\": true,\n" +
                 "        \"priority\": 1,\n" +
                 "        \"replicationRuleName\": \"my-replication-rule-2\"\n" +
@@ -157,14 +163,16 @@ public void testToJsonAndBack_sourceAndDestination() {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 ),
                 new B2ReplicationRule(
                         "my-replication-rule-2",
                         "777011112222333344445555",
                         1,
                         "abc",
-                        true
+                        true,
+                        false
                 )
         );
 
diff --git a/core/src/test/java/com/backblaze/b2/client/structures/B2BucketTest.java b/core/src/test/java/com/backblaze/b2/client/structures/B2BucketTest.java
index 258aeb32c..4846308e4 100644
--- a/core/src/test/java/com/backblaze/b2/client/structures/B2BucketTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/structures/B2BucketTest.java
@@ -59,14 +59,16 @@ public B2BucketTest() {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 ),
                 new B2ReplicationRule(
                         "my-replication-rule-2",
                         "777011112222333344445555",
                         1,
                         "abc",
-                        true
+                        true,
+                        false
                 )
         );
 
@@ -296,6 +298,7 @@ public void testFromJson() {
                 "          {\n" +
                 "            \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "            \"fileNamePrefix\": \"\",\n" +
+                "            \"includeExistingFiles\": true,\n" +
                 "            \"isEnabled\": false,\n" +
                 "            \"priority\": 3,\n" +
                 "            \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -303,6 +306,7 @@ public void testFromJson() {
                 "          {\n" +
                 "            \"destinationBucketId\": \"777011112222333344445555\",\n" +
                 "            \"fileNamePrefix\": \"abc\",\n" +
+                "            \"includeExistingFiles\": false,\n" +
                 "            \"isEnabled\": true,\n" +
                 "            \"priority\": 1,\n" +
                 "            \"replicationRuleName\": \"my-replication-rule-2\"\n" +
@@ -380,6 +384,7 @@ public void testUnauthorizedToReadServerSideEncryptionThrowsException() throws B
                 "          {\n" +
                 "            \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "            \"fileNamePrefix\": \"\",\n" +
+                "            \"includeExistingFiles\": true,\n" +
                 "            \"isEnabled\": false,\n" +
                 "            \"priority\": 3,\n" +
                 "            \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -387,6 +392,7 @@ public void testUnauthorizedToReadServerSideEncryptionThrowsException() throws B
                 "          {\n" +
                 "            \"destinationBucketId\": \"777011112222333344445555\",\n" +
                 "            \"fileNamePrefix\": \"abc\",\n" +
+                "            \"includeExistingFiles\": false,\n" +
                 "            \"isEnabled\": true,\n" +
                 "            \"priority\": 1,\n" +
                 "            \"replicationRuleName\": \"my-replication-rule-2\"\n" +
diff --git a/core/src/test/java/com/backblaze/b2/client/structures/B2CreateBucketRequestRealTest.java b/core/src/test/java/com/backblaze/b2/client/structures/B2CreateBucketRequestRealTest.java
index 01a6ad7b4..0ddded33a 100644
--- a/core/src/test/java/com/backblaze/b2/client/structures/B2CreateBucketRequestRealTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/structures/B2CreateBucketRequestRealTest.java
@@ -66,14 +66,16 @@ public void testFullCreateBucketRequestReal() {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 ),
                 new B2ReplicationRule(
                         "my-replication-rule-2",
                         "777011112222333344445555",
                         1,
                         "abc",
-                        true
+                        true,
+                        false
                 )
         );
         final Map<String, String> sourceToDestinationKeyMapping = mapOf(
@@ -151,6 +153,7 @@ public void testFullCreateBucketRequestReal() {
                 "        {\n" +
                 "          \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "          \"fileNamePrefix\": \"\",\n" +
+                "          \"includeExistingFiles\": true,\n" +
                 "          \"isEnabled\": false,\n" +
                 "          \"priority\": 3,\n" +
                 "          \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -158,6 +161,7 @@ public void testFullCreateBucketRequestReal() {
                 "        {\n" +
                 "          \"destinationBucketId\": \"777011112222333344445555\",\n" +
                 "          \"fileNamePrefix\": \"abc\",\n" +
+                "          \"includeExistingFiles\": false,\n" +
                 "          \"isEnabled\": true,\n" +
                 "          \"priority\": 1,\n" +
                 "          \"replicationRuleName\": \"my-replication-rule-2\"\n" +
diff --git a/core/src/test/java/com/backblaze/b2/client/structures/B2ReplicationRuleTest.java b/core/src/test/java/com/backblaze/b2/client/structures/B2ReplicationRuleTest.java
index 7032a06a5..61903c4f4 100644
--- a/core/src/test/java/com/backblaze/b2/client/structures/B2ReplicationRuleTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/structures/B2ReplicationRuleTest.java
@@ -16,6 +16,7 @@ public void testToJsonAndBack() {
         final String jsonString = "{\n" +
                 "  \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "  \"fileNamePrefix\": \"\",\n" +
+                "  \"includeExistingFiles\": true,\n" +
                 "  \"isEnabled\": false,\n" +
                 "  \"priority\": 3,\n" +
                 "  \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -31,10 +32,37 @@ public void testToJsonAndBack() {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 );
         final String convertedJson = B2Json.toJsonOrThrowRuntime(defaultConfig);
         assertEquals(defaultConfig, converted);
         assertEquals(jsonString, convertedJson);
     }
-}
\ No newline at end of file
+
+    @Test
+    public void testFromJsonWithOptionalFieldsNotSet() {
+        final String jsonString = "{\n" +
+                "  \"destinationBucketId\": \"000011112222333344445555\",\n" +
+                "  \"fileNamePrefix\": \"\",\n" +
+                "  \"isEnabled\": false,\n" +
+                "  \"priority\": 3,\n" +
+                "  \"replicationRuleName\": \"my-replication-rule\"\n" +
+                "}";
+        final B2ReplicationRule converted =
+                B2Json.fromJsonOrThrowRuntime(
+                        jsonString,
+                        B2ReplicationRule.class
+                );
+        final B2ReplicationRule defaultConfig =
+                new B2ReplicationRule(
+                        "my-replication-rule",
+                        "000011112222333344445555",
+                        3,
+                        "",
+                        false,
+                        false
+                );
+        assertEquals(defaultConfig, converted);
+    }
+}
diff --git a/core/src/test/java/com/backblaze/b2/client/structures/B2UpdateBucketRequestTest.java b/core/src/test/java/com/backblaze/b2/client/structures/B2UpdateBucketRequestTest.java
index bc1095631..f7d22a747 100644
--- a/core/src/test/java/com/backblaze/b2/client/structures/B2UpdateBucketRequestTest.java
+++ b/core/src/test/java/com/backblaze/b2/client/structures/B2UpdateBucketRequestTest.java
@@ -87,14 +87,16 @@ public void testFullUpdateBucketRequest() {
                         "000011112222333344445555",
                         3,
                         "",
-                        false
+                        false,
+                        true
                 ),
                 new B2ReplicationRule(
                         "my-replication-rule-2",
                         "777011112222333344445555",
                         1,
                         "abc",
-                        true
+                        true,
+                        false
                 )
         );
         final Map<String, String> sourceToDestinationKeyMapping = mapOf(
@@ -189,6 +191,7 @@ public void testFullUpdateBucketRequest() {
                 "        {\n" +
                 "          \"destinationBucketId\": \"000011112222333344445555\",\n" +
                 "          \"fileNamePrefix\": \"\",\n" +
+                "          \"includeExistingFiles\": true,\n" +
                 "          \"isEnabled\": false,\n" +
                 "          \"priority\": 3,\n" +
                 "          \"replicationRuleName\": \"my-replication-rule\"\n" +
@@ -196,6 +199,7 @@ public void testFullUpdateBucketRequest() {
                 "        {\n" +
                 "          \"destinationBucketId\": \"777011112222333344445555\",\n" +
                 "          \"fileNamePrefix\": \"abc\",\n" +
+                "          \"includeExistingFiles\": false,\n" +
                 "          \"isEnabled\": true,\n" +
                 "          \"priority\": 1,\n" +
                 "          \"replicationRuleName\": \"my-replication-rule-2\"\n" +