How to change Sales Order Item using API or best method to do so..

 Hello,

    I need to write a procedure to change the item of a sales order line.  I am trying to us the Process Order API.

   I currently have a procedure that calls this that can change the ordered quantity of the sales order line.  I pass in  (Header_id, Line_id, field_name,field value).  The header_id , line_id is the oe_order_lines_all header_id,  and line_id that i need to update.  I pass for the field name  -'ordered_quantity',  and for the field value,  i pass the quantiy that is needed,  example 10).     This procedure works just fine.