Add data to excell file with datasink without deleting existing data

Unfortunately, appending to an Excel file isn't supported. But, we have a corresponding feature request in our DB: "Add possibility to append data to a single Excel file from several DataSinks".

In the meantime, you can use DataSink of the File type, save the data to a single .csv file (enable the "append to existing file" option for that), and work with the resulting .csv file in Excel.

If it is important for you to use the excel I can offer you the workaround https://www.screencast.com/t/IRe7uYkIrg. You need to add the below Groovy script to the Setup Script for each of your TestCases, and add a new property to TestSuite. Also, please take into account that this script works with a file of Excel type of Microsoft Office 1997-2003.
Script:
 import jxl.*

  def f = new File("FullPath to .xls file")
  def wk = Workbook.getWorkbook(f)
  s1 = wk.getSheet("SheetID")
  String rows = s1.getRows()+1
  testRunner.testCase.testSuite.setPropertyValue("row", "A"+rows)