Hi angelkothari ,
Thanks for your post.
Sorry, but I don't get you.
When you create a PO in ATUM free, the products' stock is added when the order is changed to 'completed'. If you want to modify the PO before it's completed, you need to manually modify the items. Are you asking about updating the items when a product is sold?
If not, please try to explain a little further what you're asking. Images and/or examples would help.
Best Regards,
José Andrés