diff --git a/Classes/ContentObject/JsonContentObject.php b/Classes/ContentObject/JsonContentObject.php
index b7045281..fd6adb2a 100755
--- a/Classes/ContentObject/JsonContentObject.php
+++ b/Classes/ContentObject/JsonContentObject.php
@@ -69,7 +69,7 @@ public function render($conf = []): string
             $data = $this->cObjGet($conf['fields.']);
         }
         if (isset($conf['dataProcessing.'])) {
-            $data = $this->processFieldWithDataProcessing($conf);
+            $data = $this->processFieldWithDataProcessing($conf, $data);
         }
 
         $json = '';
@@ -104,7 +104,6 @@ public function cObjGet(array $setup, string $addKey = ''): array
             $theValue = $setup[$theKey];
             if ((string)$theKey && !str_contains($theKey, '.')) {
                 $conf = $setup[$theKey . '.'] ?? [];
-                $contentDataProcessing['dataProcessing.'] = $conf['dataProcessing.'] ?? [];
                 $content[$theKey] = $this->cObj->cObjGetSingle($theValue, $conf, $addKey . $theKey);
                 if ((isset($conf['intval']) && $conf['intval']) || $theValue === 'INT') {
                     $content[$theKey] = (int)$content[$theKey];
@@ -124,19 +123,24 @@ public function cObjGet(array $setup, string $addKey = ''): array
                 if ((int)($conf['ifEmptyUnsetKey'] ?? 0) === 1 && ($content[$theKey] === '' || $content[$theKey] === false)) {
                     unset($content[$theKey]);
                 }
-                if (!empty($contentDataProcessing['dataProcessing.'])) {
-                    $content[rtrim($theKey, '.')] = $this->processFieldWithDataProcessing($contentDataProcessing);
+                if (!empty($conf['dataProcessing.'] ?? [])) {
+                    $content[rtrim($theKey, '.')] = $this->processFieldWithDataProcessing(
+                        $conf,
+                        $content[rtrim($theKey, '.')]
+                    );
                 }
             }
             if ((string)$theKey && strpos($theKey, '.') > 0 && !isset($setup[rtrim($theKey, '.')])) {
                 $contentFieldName = $theValue['source'] ?? rtrim($theKey, '.');
-                $contentFieldTypeProcessing['dataProcessing.'] = $theValue['dataProcessing.'] ?? [];
 
                 if (array_key_exists('fields.', $theValue)) {
                     $content[$contentFieldName] = $this->cObjGet($theValue['fields.']);
                 }
-                if (!empty($contentFieldTypeProcessing['dataProcessing.'])) {
-                    $content[rtrim($theKey, '.')] = $this->processFieldWithDataProcessing($contentFieldTypeProcessing);
+                if (!empty($theValue['dataProcessing.'] ?? [])) {
+                    $content[rtrim($theKey, '.')] = $this->processFieldWithDataProcessing(
+                        $theValue,
+                        $content[rtrim($theKey, '.')] ?? null
+                    );
                 }
             }
         }
@@ -162,11 +166,10 @@ protected function filterByStringKeys(array $setupArr, bool $acceptAnyKeys = fal
         return array_unique($filteredKeys);
     }
 
-    /**
-     * @param array $dataProcessing
-     */
-    protected function processFieldWithDataProcessing(array $dataProcessing): mixed
+    protected function processFieldWithDataProcessing(array $conf, mixed $fieldsData = null): mixed
     {
+        $dataProcessing['dataProcessing.'] = $conf['dataProcessing.'] ?? [];
+
         $data = $this->contentDataProcessor->process(
             $this->cObj,
             $dataProcessing,
@@ -183,7 +186,8 @@ protected function processFieldWithDataProcessing(array $dataProcessing): mixed
                 $dataProcessingData = $data[$value];
             }
         }
-        return $dataProcessingData;
+        $merge = ((int)($conf['merge'] ?? 0) === 1) && is_array($fieldsData) && is_array($dataProcessingData);
+        return $merge ? array_merge($fieldsData, $dataProcessingData) : $dataProcessingData;
     }
 
     /**
diff --git a/Tests/Unit/ContentObject/JsonContentObjectTest.php b/Tests/Unit/ContentObject/JsonContentObjectTest.php
index dd041fc7..8e3733d7 100644
--- a/Tests/Unit/ContentObject/JsonContentObjectTest.php
+++ b/Tests/Unit/ContentObject/JsonContentObjectTest.php
@@ -181,11 +181,13 @@ public static function dataProvider(): array
             [['fields.' => ['test' => 'INT', 'test.' => ['value' => 1]]], json_encode(['test' => 1])],
             [['fields.' => ['test' => 'BOOL', 'test.' => ['value' => 0]]], json_encode(['test' => false])],
             [['fields.' => ['test' => 'BOOL', 'test.' => ['value' => 1]]], json_encode(['test' => true])],
-            [['fields.' => ['test' => 'BOOL', 'test.' => ['value' => 1], 'nested.' => ['fields.' => ['nestedTest' => 'INT', 'nestedTest.' => ['value' => 10]]] ]], json_encode(['test' => true, 'nested' => ['nestedTest' => 10]])],
+            [['fields.' => ['test' => 'BOOL', 'test.' => ['value' => 1], 'nested.' => ['fields.' => ['nestedTest' => 'INT', 'nestedTest.' => ['value' => 10]]]]], json_encode(['test' => true, 'nested' => ['nestedTest' => 10]])],
             [['fields.' => ['test' => 'BOOL', 'test.' => ['value' => 1], 'nested.' => ['fields.' => ['nestedTest' => 'INT', 'nestedTest.' => ['dataProcessing.' => ['10' => 'FriendsOfTYPO3\Headless\Tests\Unit\ContentObject\DataProcessingExample', '10.' => ['as' => 'sites']]]]]]], json_encode(['test' => true, 'nested' => ['nestedTest' => ['SomeCustomProcessing']]])],
             [['fields.' => ['test' => 'FLOAT', 'test.' => ['value' => 12.34]]], json_encode(['test' => 12.34])],
             [['fields.' => ['test' => 'USER_INT', 'test.' => ['userFunc' => 'FriendsOfTYPO3\Headless\Tests\Unit\ContentObject\ExampleUserFunc->someUserFunc']]], json_encode(['test' => 'HEADLESS_INT_START<<<!--INT_SCRIPT.202cb962ac59075b964b07152d234b70-->>>HEADLESS_INT_END'])],
             [['fields.' => ['test' => 'USER', 'test.' => ['userFunc' => 'FriendsOfTYPO3\Headless\Tests\Unit\ContentObject\ExampleUserFunc->someUserFunc']]], json_encode(['test' => ['test2' => 'someExtraCustomData']])],
+            [['dataProcessing.' => ['10' => 'FriendsOfTYPO3\Headless\Tests\Unit\ContentObject\DataProcessingExample', '10.' => ['as' => 'sites']], 'merge' => '1', 'fields.' => ['test' => 'TEXT', 'test.' => ['value' => '1']]], json_encode(['test' => '1', 'SomeCustomProcessing'])],
+            [['fields.' => ['test.' => ['dataProcessing.' => ['10' => 'FriendsOfTYPO3\Headless\Tests\Unit\ContentObject\DataProcessingExample', '10.' => ['as' => 'sites']], 'merge' => '1', 'fields.' => ['nested' => 'TEXT', 'nested.' => ['value' => '1']]]]], json_encode(['test' => ['nested' => '1', 'SomeCustomProcessing']])],
         ];
     }
 }