Looks like your requirement is only to have this PO’s back in backend, but you are not expecting the PO-Ack/response back from backend. You can achive it.
As RMG suggested if you have send to Backend process step you can do that, but your process instances status will again be active from completed/errord out etc.
If you can control (stop sending) the response document from backend which your process instance is expecting in process, its advisable to use “Send to backend” step again else, get the payload from RNO and work on some service(manual solution) to post it to your backend.
#Integration-Server-and-ESB#B2B-Integration#webMethods