I have 3 custom fields x_Qty , x_assigned and x_balance in parent task level . In x_qty , I will get the quantity value from sale_line_id.product_uom_qty (Sales order Line) . 

   x_balance = x_Qty - x_assigned (x_assigned=>any input value from user)

In subtask level , I want to display consolidated or calculated  x_balance value of parent task . 

Is there any way to get the calculated  value in parent task level to all of its subtasks ?