Fill backorders?

[cci1]

How does one fill backorders in Magento 2? I cannot find anywhere a Fill Backorders menu/command. 

How is one supposed to know which orders are backordered and fill them all when receiving new inventory?

Using Magento 2.1.9

Thanks!

[Tarandeep Singh]

@cci1A new order will have Pending / Processing status. While shipping those order you may find that inventory is out of stock and these are backorders.

Create a customer order status let say 'BackOrdered' and while processing orders having out of stock items, set those order status to 'BackOrdered'. In future once you have inventory available just look for the orders having status as 'BackOrdered' and process them.

Problem solved? Please give Kudo and accept as solution.

[cci1]

That might work for a few orders a day, but we are running 500+ orders a day. That just wont work, it needs to be automatic. 

[Tarandeep Singh]

There is no such feature comes in Magento by default. Should be achievable
easily by some customization. How do you process you regular orders? Do you
have some automation in place for them?

[cci1]

Our orders are auto invoiced. Twice a day our Warehouse Management System retrieves all the new orders (via an integration API) and process them. They are picked, packed  and shipped. Then at the end of each day the WMS returns the shipments and tracking info to Magento, as well as the current inventory levels. 

I have never see a ecommerce system that "allows backorders" by just having negative inventory. They always have some sort of Backorder management and filling functions. So when you receive inventory you can fill the backorders waiting for that inventory.