@Premm I suggest the custom field method for you. However, order management must be added in the future, it must be automatic. By clicking on purchase order or sales orders, you should see the order total, the delivered or invoiced total and the remaining order total.
So whenever you receive a purchase invoice for example, you check the purchase order number on the invoice, search and click to view the order and select copy to invoice. Manager would then subtract the invoice amount from the order total (tracking the delivery of individual items on the order) and display the balance on the order. Same if you received goods. If you received goods and entered it against the order and the invoice came later, enter the invoice with the goods received number, so manager will know by the goods received number that that the amount has been deducted from the order already, if there are extra cost lines on the invoice manager should compare and deduct only those from the order.
Same will be for sales order management
And when the delivery date passes the app should tell you by maybe changing the remaining order amount to red or something or flag it.
Order management is a very important tool in supply chain and procurement management in the modern business
This is the only thing I envy about quick books as compared to Manager. It automatically tracks Inventory and Non inventory items on orders and shows their balances. It even tells you you have an order pending for a particular vendor if you select them for a new purchase invoice (Same for customers on entering sales invoices)
I have ideas to suggest but I want to wait for many crucial features to be implemented first.
@Tut @lubos @Brucanna comments?