I have a child table (depuratori) with a foreign key to a parent table (reti). The parent table has a primary key and two foreign key, no other fields. I have setup the form widget to "Relation Reference".
My problem is that in the "Display expression" of the Relation Reference I can select only the foreign keys of the parent table that are not "human readable". Is there a function (like represent_value() for the Value Map) that retrieve and display the foreign keys of the parent?