Dear,
Yes that's true but you have only release orders as per your posting.
PO1 is already released.No confirmation has been carried yet.
Now I have added one more activity in WC1, say LABOUR LC1.
I have nearly 500 production orders already released with work center WC1.
Anyway once you do partial confirmation or good movement after that you do any changes to an order will create variance which is not a part practice. I will suggest reverse the confirmation and good movement and TECO all orders and create fresh orders.
Regards,
R.Brahmankar