I'm trying to change a Woocommerce SKU (most likely add a suffix) if a product is on backorder. Reason being is accounting related with integration to Xero which doesn't have a facility for backorders.
So if stock is 10 SKU = PRODABC but if stock is =<0 then SKU = PRODABC-BK
I've searched high and low for a solution but cannot find anything.
Any help would be greatly appreciated