diff --git a/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryEnsembleTools.cpp b/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryEnsembleTools.cpp
index f869e6136b..53b1b0bd97 100644
--- a/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryEnsembleTools.cpp
+++ b/ApplicationLibCode/ProjectDataModel/Summary/RimSummaryEnsembleTools.cpp
@@ -416,16 +416,29 @@ void RimSummaryEnsembleTools::highlightCurvesForSummaryCases( const std::vector<
             if ( plot->curveSets().empty() ) continue;
 
             std::vector<RimPlotCurve*> curvesForSameRealization;
+            std::vector<RimPlotCurve*> curvesInScope;
             for ( const auto& curveSet : plot->curveSets() )
             {
+                std::vector<RimPlotCurve*> curvesInCurveSet;
+                bool                       curveSetContainsSourceCase = false;
+
                 for ( auto ensembleCurve : curveSet->curves() )
                 {
+                    curvesInCurveSet.push_back( ensembleCurve );
+
                     auto summaryCaseY = ensembleCurve->summaryCaseY();
                     if ( std::find( sourceCases.begin(), sourceCases.end(), summaryCaseY ) != sourceCases.end() )
                     {
                         curvesForSameRealization.push_back( ensembleCurve );
+                        curveSetContainsSourceCase = true;
                     }
                 }
+
+                // Only curve sets containing a selected case participate in dimming, so curves from other ensembles are left unchanged.
+                if ( curveSetContainsSourceCase )
+                {
+                    curvesInScope.insert( curvesInScope.end(), curvesInCurveSet.begin(), curvesInCurveSet.end() );
+                }
             }
 
             bool updateCurveOrder = false;
@@ -437,7 +450,7 @@ void RimSummaryEnsembleTools::highlightCurvesForSummaryCases( const std::vector<
                 curvesForSameRealization.erase( std::unique( curvesForSameRealization.begin(), curvesForSameRealization.end() ),
                                                 curvesForSameRealization.end() );
 
-                plotWidget->highlightCurvesUpdateOrder( curvesForSameRealization );
+                plotWidget->highlightCurvesUpdateOrder( curvesForSameRealization, curvesInScope );
             }
 
             plotWidget->replot();
diff --git a/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.cpp b/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.cpp
index c8cf92869f..7990e9dfa3 100644
--- a/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.cpp
+++ b/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.cpp
@@ -1098,9 +1098,9 @@ void RiuQwtPlotWidget::replot()
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------
-void RiuQwtPlotWidget::highlightCurvesUpdateOrder( const std::vector<RimPlotCurve*>& curves )
+void RiuQwtPlotWidget::highlightCurvesUpdateOrder( const std::vector<RimPlotCurve*>& curves, const std::vector<RimPlotCurve*>& curvesInScope )
 {
-    highlightPlotCurves( curves );
+    highlightPlotCurves( curves, curvesInScope );
 
     updateCurveOrder();
 }
@@ -1108,7 +1108,7 @@ void RiuQwtPlotWidget::highlightCurvesUpdateOrder( const std::vector<RimPlotCurv
 //--------------------------------------------------------------------------------------------------
 ///
 //--------------------------------------------------------------------------------------------------
-void RiuQwtPlotWidget::highlightPlotCurves( const std::vector<RimPlotCurve*>& curves )
+void RiuQwtPlotWidget::highlightPlotCurves( const std::vector<RimPlotCurve*>& curves, const std::vector<RimPlotCurve*>& curvesInScope )
 {
     if ( !m_plotDefinition || !m_plotDefinition->isCurveHighlightSupported() )
     {
@@ -1128,6 +1128,12 @@ void RiuQwtPlotWidget::highlightPlotCurves( const std::vector<RimPlotCurve*>& cu
         // manipulation
         if ( !currentRimPlotCurve ) continue;
 
+        // When a scope is provided, only curves inside the scope are processed. Curves outside the scope are left untouched.
+        if ( !curvesInScope.empty() && std::find( curvesInScope.begin(), curvesInScope.end(), currentRimPlotCurve ) == curvesInScope.end() )
+        {
+            continue;
+        }
+
         auto* plotCurve = dynamic_cast<QwtPlotCurve*>( plotItem );
         if ( plotCurve )
         {
diff --git a/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.h b/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.h
index 6fa3842dfb..50b4dbd2be 100644
--- a/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.h
+++ b/ApplicationLibCode/UserInterface/RiuQwtPlotWidget.h
@@ -162,9 +162,9 @@ public:
 
     QwtAxisId toQwtPlotAxis( RiuPlotAxis axis ) const;
 
-    void                                       highlightPlotItem( const QwtPlotItem* plotItem );
-    void                                       highlightCurvesUpdateOrder( const std::vector<RimPlotCurve*>& curves );
-    void                                       resetPlotItemHighlighting( bool doUpdateCurveOrder = true );
+    void highlightPlotItem( const QwtPlotItem* plotItem );
+    void highlightCurvesUpdateOrder( const std::vector<RimPlotCurve*>& curves, const std::vector<RimPlotCurve*>& curvesInScope = {} );
+    void resetPlotItemHighlighting( bool doUpdateCurveOrder = true );
     std::vector<caf::PdmPointer<RimPlotCurve>> highlightedCurves() const;
 
     void replot() override;
@@ -211,7 +211,7 @@ private:
 
     void highlightPlotAxes( QwtAxisId axisIdX, QwtAxisId axisIdY );
     void highlightPlotItemsForQwtAxis( QwtAxisId axisId );
-    void highlightPlotCurves( const std::vector<RimPlotCurve*>& curves );
+    void highlightPlotCurves( const std::vector<RimPlotCurve*>& curves, const std::vector<RimPlotCurve*>& curvesInScope = {} );
     void highlightPlotShapeItems( const std::set<const QwtPlotItem*>& closestItems );
     void resetPlotCurveHighlighting();
     void resetPlotShapeItemHighlighting();