You can do this by first downloading your invoicees using: getinvoiceescsv
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 InvoiceeId number must be blank (or the column removed) to add a new invoicee or the Invoicee number of an existing invoicee to modify it.
A new invoicee must have a name.
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.
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.