diff --git a/python/gui/auto_generated/editorwidgets/qgsrelationreferencewidget.sip.in b/python/gui/auto_generated/editorwidgets/qgsrelationreferencewidget.sip.in
index 2117185655d..d54195fc50c 100644
--- a/python/gui/auto_generated/editorwidgets/qgsrelationreferencewidget.sip.in
+++ b/python/gui/auto_generated/editorwidgets/qgsrelationreferencewidget.sip.in
@@ -46,7 +46,7 @@ class QgsRelationReferenceWidget : QWidget
 
     void setRelationEditable( bool editable );
 
-    void setForeignKey( const QVariant &value );
+ void setForeignKey( const QVariant &value ) /Deprecated/;
 %Docstring
 this sets the related feature using from the foreign key
 
diff --git a/src/gui/editorwidgets/qgsrelationreferencewidget.cpp b/src/gui/editorwidgets/qgsrelationreferencewidget.cpp
index 73d635c8994..def0ed69de7 100644
--- a/src/gui/editorwidgets/qgsrelationreferencewidget.cpp
+++ b/src/gui/editorwidgets/qgsrelationreferencewidget.cpp
@@ -48,7 +48,7 @@
 bool qVariantListIsNull( const QVariantList &list )
 {
   if ( list.isEmpty() )
-    return false;
+    return true;
 
   for ( int i = 0; i < list.size(); ++i )
   {
@@ -271,7 +271,7 @@ void QgsRelationReferenceWidget::setForeignKey( const QVariant &value )
 
 void QgsRelationReferenceWidget::setForeignKeys( const QVariantList &values )
 {
-  if ( !values.isEmpty() )
+  if ( values.isEmpty() )
   {
     return;
   }
@@ -291,7 +291,8 @@ void QgsRelationReferenceWidget::setForeignKeys( const QVariantList &values )
     // Set the value on the foreign key fields of the referencing record
 
     const QList<QgsRelation::FieldPair> fieldPairs = mRelation.fieldPairs();
-    for ( int i = 0; i < fieldPairs.count(); i++ )
+    int fieldCount = std::min( fieldPairs.count(), values.count() );
+    for ( int i = 0; i < fieldCount; i++ )
     {
       int idx = mReferencingLayer->fields().lookupField( fieldPairs.at( i ).referencingField() );
       attrs[idx] = values.at( i );
@@ -307,7 +308,7 @@ void QgsRelationReferenceWidget::setForeignKeys( const QVariantList &values )
     }
 
     mForeignKeys.clear();
-    for ( const QString &fieldName : mReferencedFields )
+    for ( const QString &fieldName : qgis::as_const( mReferencedFields ) )
       mForeignKeys << mFeature.attribute( fieldName );
 
     QgsExpression expr( mReferencedLayer->displayExpression() );
@@ -317,7 +318,7 @@ void QgsRelationReferenceWidget::setForeignKeys( const QVariantList &values )
     if ( expr.hasEvalError() )
     {
       QStringList titleFields;
-      for ( const QString &fieldName : mReferencedFields )
+      for ( const QString &fieldName : qgis::as_const( mReferencedFields ) )
         titleFields << mFeature.attribute( fieldName ).toString();
       title = titleFields.join( QStringLiteral( " " ) );
     }
@@ -373,7 +374,7 @@ void QgsRelationReferenceWidget::deleteForeignKeys()
     }
     mLineEdit->setText( nullText );
     QVariantList nullAttributes;
-    for ( const QString &fieldName : mReferencedFields )
+    for ( const QString &fieldName : qgis::as_const( mReferencedFields ) )
     {
       Q_UNUSED( fieldName );
       nullAttributes << QVariant( QVariant::Int );
@@ -784,13 +785,13 @@ void QgsRelationReferenceWidget::featureIdentified( const QgsFeature &feature )
     if ( expr.hasEvalError() )
     {
       QStringList titleFields;
-      for ( const QString &fieldName : mReferencedFields )
+      for ( const QString &fieldName : qgis::as_const( mReferencedFields ) )
         titleFields << mFeature.attribute( fieldName ).toString();
       title = titleFields.join( QStringLiteral( " " ) );
     }
     mLineEdit->setText( title );
     mForeignKeys.clear();
-    for ( const QString &fieldName : mReferencedFields )
+    for ( const QString &fieldName : qgis::as_const( mReferencedFields ) )
       mForeignKeys << mFeature.attribute( fieldName );
     mFeature = feature;
   }
@@ -956,8 +957,8 @@ void QgsRelationReferenceWidget::addEntry()
   if ( mEditorContext.vectorLayerTools()->addFeature( mReferencedLayer, attributes, QgsGeometry(), &f ) )
   {
     QVariantList attrs;
-    for ( const QString &fieldName : mReferencedFields )
-      attrs << mFeature.attribute( fieldName );
+    for ( const QString &fieldName : qgis::as_const( mReferencedFields ) )
+      attrs << f.attribute( fieldName );
 
     mComboBox->setIdentifierValues( attrs );
 
diff --git a/src/gui/editorwidgets/qgsrelationreferencewidget.h b/src/gui/editorwidgets/qgsrelationreferencewidget.h
index 99f10c1c0c7..a1b6edc2103 100644
--- a/src/gui/editorwidgets/qgsrelationreferencewidget.h
+++ b/src/gui/editorwidgets/qgsrelationreferencewidget.h
@@ -87,7 +87,7 @@ class GUI_EXPORT QgsRelationReferenceWidget : public QWidget
      * this sets the related feature using from the foreign key
      * \deprecated since QGIS 3.10 use setForeignKeys
      */
-    void setForeignKey( const QVariant &value );
+    Q_DECL_DEPRECATED void setForeignKey( const QVariant &value ) SIP_DEPRECATED;
 
     /**
      * Sets the related feature using the foreign keys
diff --git a/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp b/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp
index 8337e86c2d1..27d0912831c 100644
--- a/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp
+++ b/src/gui/editorwidgets/qgsrelationreferencewidgetwrapper.cpp
@@ -146,7 +146,8 @@ QVariantList QgsRelationReferenceWidgetWrapper::additionalFieldValues() const
   {
     QVariantList values = mWidget->foreignKeys();
     const QList<QgsRelation::FieldPair> fieldPairs = mWidget->relation().fieldPairs();
-    for ( int i = 0; i < fieldPairs.count(); i++ )
+    int fieldCount = std::min( fieldPairs.count(), values.count() );
+    for ( int i = 0; i < fieldCount; i++ )
     {
       if ( fieldPairs.at( i ).referencingField() == field().name() )
       {
diff --git a/src/gui/qgsfeaturelistcombobox.cpp b/src/gui/qgsfeaturelistcombobox.cpp
index d2c74c34cab..fe95578d4d7 100644
--- a/src/gui/qgsfeaturelistcombobox.cpp
+++ b/src/gui/qgsfeaturelistcombobox.cpp
@@ -82,7 +82,7 @@ void QgsFeatureListComboBox::setCurrentFeature( const QgsFeature &feature )
   {
     values << feature.attribute( field );
   }
-  setCurrentIndex( findData( values, QgsFeatureFilterModel::Role::IdentifierValueRole ) );
+  setIdentifierValues( values );
 }
 
 QString QgsFeatureListComboBox::displayExpression() const
diff --git a/tests/src/gui/testqgsrelationreferencewidget.cpp b/tests/src/gui/testqgsrelationreferencewidget.cpp
index 7713b249e51..99510634f1a 100644
--- a/tests/src/gui/testqgsrelationreferencewidget.cpp
+++ b/tests/src/gui/testqgsrelationreferencewidget.cpp
@@ -249,17 +249,17 @@ void TestQgsRelationReferenceWidget::testChainFilterRefreshed()
   QCOMPARE( cbs[2]->currentText(), QString( "raccord" ) );
 
   // update foreign key
-  w.setForeignKey( QVariant( 12 ) );
+  w.setForeignKeys( QVariantList() << QVariant( 12 ) );
   QCOMPARE( cbs[0]->currentText(), QString( "steel" ) );
   QCOMPARE( cbs[1]->currentText(), QString( "120" ) );
   QCOMPARE( cbs[2]->currentText(), QString( "collar" ) );
 
-  w.setForeignKey( QVariant( 10 ) );
+  w.setForeignKeys( QVariantList() << QVariant( 10 ) );
   QCOMPARE( cbs[0]->currentText(), QString( "iron" ) );
   QCOMPARE( cbs[1]->currentText(), QString( "120" ) );
   QCOMPARE( cbs[2]->currentText(), QString( "brides" ) );
 
-  w.setForeignKey( QVariant( 11 ) );
+  w.setForeignKeys( QVariantList() << QVariant( 11 ) );
   QCOMPARE( cbs[0]->currentText(), QString( "iron" ) );
   QCOMPARE( cbs[1]->currentText(), QString( "120" ) );
   QCOMPARE( cbs[2]->currentText(), QString( "sleeve" ) );
@@ -289,7 +289,7 @@ void TestQgsRelationReferenceWidget::testChainFilterDeleteForeignKey()
   QCOMPARE( cbs[2]->isEnabled(), false );
 
   // set a foreign key
-  w.setForeignKey( QVariant( 11 ) );
+  w.setForeignKeys( QVariantList() << QVariant( 11 ) );
 
   QCOMPARE( cbs[0]->currentText(), QString( "iron" ) );
   QCOMPARE( cbs[1]->currentText(), QString( "120" ) );
@@ -328,18 +328,18 @@ void TestQgsRelationReferenceWidget::testSetGetForeignKey()
 
   QSignalSpy spy( &w, SIGNAL( foreignKeyChanged( QVariant ) ) );
 
-  w.setForeignKey( 11 );
-  QCOMPARE( w.foreignKey(), QVariant( 11 ) );
+  w.setForeignKeys( QVariantList() << 11 );
+  QCOMPARE( w.foreignKeys().at( 0 ), QVariant( 11 ) );
   QCOMPARE( w.mComboBox->currentText(), QStringLiteral( "(11)" ) );
   QCOMPARE( spy.count(), 1 );
 
-  w.setForeignKey( 12 );
-  QCOMPARE( w.foreignKey(), QVariant( 12 ) );
+  w.setForeignKeys( QVariantList() << 12 );
+  QCOMPARE( w.foreignKeys().at( 0 ), QVariant( 12 ) );
   QCOMPARE( w.mComboBox->currentText(), QStringLiteral( "(12)" ) );
   QCOMPARE( spy.count(), 2 );
 
-  w.setForeignKey( QVariant( QVariant::Int ) );
-  Q_ASSERT( w.foreignKey().isNull() );
+  w.setForeignKeys( QVariantList() << QVariant( QVariant::Int ) );
+  Q_ASSERT( w.foreignKeys().at( 0 ).isNull() );
   QCOMPARE( spy.count(), 3 );
 }