if Possible add in the Sale Invoice Previous Balance, Current Bill, Current Balance for All Customer. 10000 is Cash In this bill . this will be add in the Uper side at the Invoice
Pervious Balance : 100000 Dr
Current Bill : 20000
Current Balance : 110000 Dr
Why not attach to your invoice a Customer Statement?
how i Attached
Generate a Customer Statement pdf and send it together with the pdf of the Invoice.