(Please forgive the very crude paintshop editing....)
Whenever we do purchase orders, we reorder required stock levels, but it's always nice to tweak levels.
I think it would hugely beneficial for the mandatory columns to include:
1. Real Time Stock Level
2. Last Qty Ordered
3. Date of last Delivery
Take the titles with a pinch of salt, but hopefully you get the idea.
This information is already available outside the PO screen, but having all necessary information in one location would be preferable.
That way, you could work your way through getting all the information you could possibly need to add or remove items from the PO you are working on.