You can do this by first downloading your invoices using: getinvoicescsv
The first row must contain the header for each colum to identify the contents of that column. Each following row contains one invoice item.
Data has to be entered exactly in the required format and position otherwise the import can not work or will import false data.
The Bookid value must be specified for all invoice items.
The Itemid number must be blank for a new invoice item or the Itemid number of an existing invoice item to modify or delete it.
To delete an invoice item, set all its values to blank (empty string) except for Bookid and Itemid.
Not all columns can be imported, the preview will show the information that will be imported.
Upload the file WITHOUT ticking the "Save Changes" checkbox. A report will be shown of the information read from the file. If the preview shows errors fix them in your CSV file and upload again.
You should only use this function if you are comfortable working with CSV files.
It is a good idea to test with just a few invoices and upload a maximum of 1000 invoice items at a time. It can take up to a minute to process a file, do not re-click submit while the file is processing or you may end up with duplicate imports.
The data fields (columns) must not contain the data seperator character within the data (comma, tab or semicolon) unless the whole field is enclosed in double quotes.
To check your file format import it into your spreadsheet with only a comma, tab or semicolon allowed as the field seperator.