In ppvote Matrix, live data, postal votes and benchmark data can all be edited/imported using the Excel based Data editor.
Within Matrix go to File > Data > Edit. Click on Modify data in Excel. This will generate a spreadsheet where benchmark data and postal votes can set up ready for import.
If you have live voting data, that will also be included in the spreadsheet and you will be able to edit that if required.
Note, it's best to have Excel closed before generating the template.
Once you have completed the spreadsheet, return to the menu and click on Import data from Excel. No need to save the spreadsheet. Just ensure that you don't have any other Excel files open when you import.