Hello,
I’m currently evaluating ERPnext for my business, and I’m very excited, this appears to be quality software 
However, one of my suppliers is a bit chaotic, and it regularly happens that I get an invoice after items are delivered, and I usually do not know the exact purchase amount before I get the invoice. So I would create the purchase order with Prices of 0, then store/book the items to a warehouse with Purchase Receipt ready to be used, and then adjust the rate when entering Purchase Invoice when I finally get the invoice. However, the Update Items button for the purchase order vanishes after entering receipt of items. Is there a way to prevent this? Wouldn’t it make more sense to lock this function only after entering the purchase invoice?
And in general: if I want to change this kind of business logic, is this a modification in the source code, or is there a frontend facing way to build and adapt changes like this?
thanks a bunch for any insight,
Philip