According to the documentation 'enabling archiving traverses relationship classes' so I enabled archiving in my non-versioned PostgreSQL feature class which participates in a feature to table relationship class, but didn't enable it in the related table.
Through pgAdmin I see the archiving fields gdb_archived_oid, gdb_from_date and gdb_to_date added for both the feature class and the related table, and I also see a _evw view for each.
Back to ArcGIS Pro, when connected to the database to a specific date and time through the History pane I see the features at that moment both in the feature class and the related table.
Everything as expected to this point.
Now I'd like to add the archive feature class and the archive related table to the Contents pane to set up my own definition queries on the history data. No problem for the archive feature class, it can be added through its feature layer's Data tab (clicking the Add archive button in the Archiving group), but I don't see how to access the archive related table. The Add archive button is grayed out because I didn't directly enable archiving for the related table.
The question is, do I have to enable archiving in the related table anyway? Cannot find documentation about this and don't know if it could have any unexpected conseqüences.