srinivas,
Perhaps you need to clear these two doubts to the forum:
- If tasklist is your issue, why can't you change it in the generated Order?
- In the extreme case, what is the problem in creating a new Order manually with your desired date and with desired tasklist?
If you are opting for a new Order, you can set the Old Order to 'Do not Execute' status.
KJogeswaraRao