Populate AP invoice approval assignee to routing attribute

Hi,

We know that the routing attributes in AP invoices come from the IDR email subject. Is it possible to override/ populate these attributes with the approval assignee (probably through BPM)?

The reason is, if someone goes into the invoice and saves it e.g. corrects a value or changes the supplier, the Assignee field is blanked out and the user can't change it. We have AP user who takes a quick look at invoices in the morning and might correct something, but someone else does most of the work on it (the Assignee). This Assignee value is being lost when the first user makes a change. In such case, the AP invoice approval will be errored.