Suppose,
ProductionDate Production Op Balance DelDate Party Qnty Cl.
Balance
1.1.09 500 500 2.1.09
Leon 300 200
2.1.09 500 700 -----
---- ---- 700
3.1.09 500 1200 ------
---- 1200
4.1.09 ---- 1200 4.1.09
David 500 700
5.1.09 --- 700 5.1.09
Mahi 300 400

Note that in case of only DelDate that follows by Production date.

Thanks