Dynamically insert Received quantity by Forward quantity in new line

1- Create three Edt with real data type
     -> S3ErrorQty
     ->  S3RecivedQty
     ->  S3ForwardQty

2 Create new table with name RejectionTable
with fields   S3ErrorQty,S3RecivedQty,S3ForwardQty

3- write a static method in tables's method node
   static int64 Returns()
{
    RejectionTable rejectionTable;
   ;
    select reverse firstOnly s3ForwardQty from RejectionTable;
    return rejectionTable.S3ForwardQty;
}

4- Create Form with data source RejectionTable

5 -write methods on form data source S3ErrorQty-modified
public void modified()
{
    super();
    RejectionTable.S3ForwardQty= RejectionTable.S3RecivedQty-RejectionTable.S3ErrorQty;
}
6-write methods on form data source S3RecivedQty-modified
 public void modified()
{
    super();
    RejectionTable.S3ForwardQty= RejectionTable.S3RecivedQty-RejectionTable.S3ErrorQty;
}
7-write create method in form's datasources-RejectionTable-Create
 public void create(boolean _append = false)
{
    super(_append);
    RejectionTable.S3RecivedQty =RejectionTable::Returns();
}