title: Write dataframe into existing sheet in excel without removing textboxes
body: <p>I have the following code to insert my dataframe into an existing sheet in excel, and it works fine except for deleting the textboxes I had in the sheets before the insertion.</p>
  <pre><code>   with pd.ExcelWriter(report_filename, mode='a', if_sheet_exists='overlay') as writer:
          results_start_column = list(test_df.columns).index(final_columns_to_copy[0])
          test_results_df[final_columns_to_copy].to_excel(writer, sheet_name=test_name, merge_cells=False, index=False, header=False, startrow=test_first_data_row + 1, startcol=results_start_column)
  </code></pre>
  <p>Is there a way to prevent the engine to delete the textboxes? Or otherwise anyone familiar with engines that don't delete it?</p>