Hi Ranjan,
The idea of the closed work status is to prevent changes to the closed period. If somebody wants to write data to the previous periods then:
1. Use other status - not closed.
2. Reopen - write - close (as now).
3. Use badi instead of script logic to write data.
4. Create data to write in some not closed category and then use copy DM package to copy data to the closed periods bypassing work status check.
Script logic is unable to write data to the closed periods!!!
B.R. Vadim