If a dropship PO gets canceled, Will the corresponding dropship sales order line get unscheduled?

We have a requirement where if supplier said he can not supply and hence PO line gets canceled through PO Change order then the corresponding SO line will be unscheduled and we need to provide supplier name/warehouse name on the order line, from where the goods will be shipped.

But when In my case when the PO gets canceled, the sales order status remains in "Requisition Created" status and on trying to manually unschedule the order it is throwing error that "This fulfillment line cannot be updated because the purchase request is at the requisition stage in the procurement application"