After a Proforma has been raise for the deposit, you can generate a proforma for the balance owed against the total value of the order
The Order Tracker is where you see all the documents related to a specific Sales Order.
You can already see the previous Deposit Proforma.
Discount comes from the Sales Order and Transport Charge comes from the Deposit Proforma.
You can see on screen the Previous Payments from previous Proformas on this order.