How to refresh QGIS Relation Reference widget without closing and reopening form?

Question

The Relation Reference widget has buttons to open a 2nd form so that records in the referenced (parent) layer can be edited or new records added.

However, when the edits are made to the parent layer and 'OK' is clicked on the 2nd form - the edits are not reflected in the list of values in the widget, unless both these are performed:

1. the parent table is saved
2. the form containing the Relation Reference widget is closed and reopened

How else can the Relation Reference widget be refreshed ?

Answer 1

By following the example in this video, I was able to get the widget to refresh automatically when a new record was added to the parent layer, and saving the parent layer is not required for the refresh.

(Note, updates to an existing record in the parent layer still aren't automatically refreshed in the widget list. However, this does not really matter, because the record is already selected and linked, its just the widget expression that doesn't refresh automatically.)