How to Apply Discount on Return Order For Particular Sales Order while changing return qty in ax 2012

Scenario : Discount for Return order for Selected SalesOrder in ax 2012 r3

Hi guys recently I got requirement on “Discount for Return order for Selected SalesOrder “

Actually as per Functionality while doing Return Order for Selected SalesOrder(i.e if Original SalesOrder is having some discpercent),here in return order line if you change qty the Original "DiscPercent" of that selected SalesOrder will not effect here So to effect " Discount for Return order" i had written following code 

Note: This Code Will Effect only if you change qty on Return Order line for selected SalesOrder 

Now go to Returntable Form >> SalesLine DataSource>>ExpectedRetQty Field>>Modified()

void  modified()

{

    SalesLine salesline1;
   // Find Original Salesorder's InventTransId by using InventTransIdReturn
   

    salesline1 = SalesLine::findInventTransId(SalesLine.InventTransIdReturn); 

    super();

    interCompanyIsPriceDiscSearchNeeded = salesLine.RecId;

    if (mcrCallCenterEnabled)

   {

        element.mcrSetLineControls();

        }
//here original Salesorder linepercent will get by above finding Inventransid by using that we can do percent calculation as below
// here Salesline1 is the Original SalesOrder Recid

    if (salesline1.LinePercent)

        {

        salesline.LineAmount = (salesline.SalesPrice -(salesline.SalesPrice*(salesline1.LinePercent/100)))*salesline.ExpectedRetQty;
salesline.LinePercent=  salesline1.LinePercent;

        }

    else

        {

        if (salesline1.LineDisc)

        {

        salesline.LineAmount = (salesline.SalesPrice - salesline1.LineDisc) * salesline.ExpectedRetQty;
        salesline.LineDisc      =  salesline1.LineDisc;

        }

        else

        {

        salesline.LineAmount = salesline.SalesPrice * salesline.ExpectedRetQty;

        }

  }

}