Previous on invoice

  1. How can i add Customer Previous balance in invoice as text just for reminding in a tab on invoice.?

  2. How can add a “non salable” item e.g gift items in invoice.?

  1. Use a custom field and enter the details manually each time - this would be very prone to errors and would not be a great solution. If you must send this information to your customers, print and attach a Customer statement

  2. just add a line with zero value