Enter a receipt route on a PO after creation

Hello.  Say for example I create a PO for an item that already has an item/supplier relationship, but has no receipt route. I create my PO, then go in P43090 to add the route before it's recieved. When I recieve that PO, even if it has a route, items won't go in receipt routing because F43092 and F43099 aren't populated, because at the time of creation, I didn't have an item/supplier/route relationship. Is there a way to enter a PO in receipt routing after it's been created?

Thanks and regards.

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Hugo Pascal