Right after a paid order comes in, the plugin moves the backordered units to a linked order in the background. The payment and WooCommerce’s normal order emails cover the whole purchase first, then the customer gets the Order split notice.
- Split partial quantities on: a line of 5 with 3 in stock becomes 3 now and 2 later. Off: the whole line waits.
- Unpaid orders, such as bank transfer, are split once they move to Processing.
- Use “Only orders with at least 2 lines” to leave single product orders alone.