AR invoice PLD reflects base Sales Order Value

Dear All,

In AR invoice PLD I need a field in which the base document total value comes. For example a Sales Order is made for 2 Items unit price USD 500 each Amouting for USD 1000 ( Sales Order Total Value ). Based on this sales order partial AR invoice is booked for 1 item USD 500.

Now I want fields in the AR invoice PLD which shows me as :

Total Order Value which is USD 1000

Current Invoice Value USD 500

Balance Invoice Value USD 500 ( which will come by total order value - current AR invoice )

Can anyone please help me how to solve this issue as it is required immediately.

Regards,

Kawish