What if a customer orders SKU 123456 but the product now has SKU 1234567 ?

Lets say you have no stock. The product is set up as MTS (make to stock) and procurement is BUY) . The PO is created and the item is then ordered from the supplier.

The problem starts when the item arrives under a new SKU from the supplier (maybe SKU is 1234567) without prior warning from the supplier.

The IN document will not contain this new SKU number but i know you can add a SKU line to the IN while receiving. So this will create the inventory for the new SKU. The warehouse person will then be expected to contact the supplier to find out why they sent a product not listed on our PO. The supplier will then inform our warehouse person that SKU 1234567 replaces 123456.

I had an idea to make the old SKU a manufactured part and the BOM (bill of materials) is just this one line (the new SKU 1234567)

The other guess is to cancel the SO (sales order) and create and new one with the new SKU. Then edit the PO and the IN document but this seems a lot of work.

what is the correct procedure ?