How to route supplier portal invoices for approval to the manager of the requester on line

Summary:

How to route supplier portal invoices for approval to the manager of the requester on the invoice line?

Content (please ensure you mask any confidential information):

My client has a requirement to route PO-matched supplier portal invoices to the manager of the requester for approval. Since the header level requester field is not shown in supplier portal, we need to use the requester on the PO-matched invoice line. I have tried multiple different ways to create the rule in BPM and it fails. Does anyone know how to achieve this in BPM?

Version (include the version you are using, if applicable):