Can I update DFF fields on an AR invoice when it has been already completed and posted to GL?

Hi folks,

We have a list of 6 AR invoices that were created manually,

somehow users forgot to populate the interface header attributes on the DFF at invoice header level.

We use those values to make the cross reference to Project # and some other values like agreeement #, draft inv # among others.

Now the problem is, when users run their AR Aging report all those invoices fall under category of NO-PROJECTS, somehow they are linking pa_projects.segment1 to ra_customer_trx.interface_header_attribute1

I have been asked to make an update in such a way that i make the cross reference to the respective proj #., in other words populate the interface_header_context and the interface_header_attributeX