add columns filling for --forked

tests/post_training/test_quantize_conformance.py

@@ -190,7 +190,22 @@ def fixture_report_data(output_dir, run_benchmark_app, pytestconfig):
         if pytestconfig.getoption("forked") and output_file.exists():
             # When run test with --forked to run test in separate process
             # Used in post_training_performance jobs
-            df.to_csv(output_file, index=False, mode="a", header=False)
+            existing_df = pd.read_csv(output_file)
+
+            # Ensure all columns are present in both DataFrames
+            for column in existing_df.columns:
+                if column not in df.columns:
+                    df[column] = None
+            for column in df.columns:
+                if column not in existing_df.columns:
+                    existing_df[column] = None
+
+            # Reorder columns to match
+            df = df[existing_df.columns]
+
+            # Append new data to existing data
+            combined_df = pd.concat([existing_df, df], ignore_index=True)
+            combined_df.to_csv(output_file, index=False)
         else:
             df.to_csv(output_file, index=False)