diff --git a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.cpp b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.cpp
index 03bbc40134..0580b7ce64 100644
--- a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.cpp
+++ b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.cpp
@@ -142,6 +142,9 @@ RimSummaryCurve::RimSummaryCurve()
 
     m_curveNameConfig = new RimSummaryCurveAutoName;
 
+    CAF_PDM_InitField(&m_isTopZWithinCategory, "isTopZWithinCategory", false, "", "", "", "");
+    m_isTopZWithinCategory.uiCapability()->setUiHidden(true);
+
     m_symbolSkipPixelDistance = 10.0f;
     m_curveThickness = 2;
 }
@@ -670,25 +673,34 @@ void RimSummaryCurve::setZIndexFromCurveInfo()
     auto sumAddr = summaryAddressY();
     auto sumCase = summaryCaseY();
 
+    double zOrder = 0.0;
+
     if (sumCase && sumAddr.isValid())
     {
         if (sumCase->isObservedData())
         {
-            setZOrder(RiuQwtPlotCurve::Z_SINGLE_CURVE_OBSERVED);
+            zOrder = RiuQwtPlotCurve::Z_SINGLE_CURVE_OBSERVED;
         }
         else if (sumAddr.category() == RifEclipseSummaryAddress::SUMMARY_ENSEMBLE_STATISTICS)
         {
-            setZOrder(RiuQwtPlotCurve::Z_ENSEMBLE_STAT_CURVE);
+            zOrder = RiuQwtPlotCurve::Z_ENSEMBLE_STAT_CURVE;
         }
         else if (sumCase->ensemble())
         {
-            setZOrder(RiuQwtPlotCurve::Z_ENSEMBLE_CURVE);
+            zOrder = RiuQwtPlotCurve::Z_ENSEMBLE_CURVE;
         }
         else
         {
-            setZOrder(RiuQwtPlotCurve::Z_SINGLE_CURVE_NON_OBSERVED);
+            zOrder = RiuQwtPlotCurve::Z_SINGLE_CURVE_NON_OBSERVED;
         }
     }
+
+    if (m_isTopZWithinCategory)
+    {
+        zOrder += 1.0;
+    }
+
+    setZOrder(zOrder);
 }
  
 //--------------------------------------------------------------------------------------------------
@@ -778,6 +790,14 @@ void RimSummaryCurve::markCachedDataForPurge()
     if(reader) reader->markForCachePurge(m_yValuesCurveVariable->address());
 }
 
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+void RimSummaryCurve::setAsTopZWithinCategory(bool enable)
+{
+    m_isTopZWithinCategory = enable;
+}
+
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
@@ -816,6 +836,11 @@ void RimSummaryCurve::fieldChangedByUi(const caf::PdmFieldHandle* changedField,
 
         RiuPlotMainWindow* mainPlotWindow = RiaApplication::instance()->mainPlotWindow();
         mainPlotWindow->updateSummaryPlotToolBar();
+
+        if (m_showCurve() == true)
+        {
+            plot->summaryCurveCollection()->setCurveAsTopZWithinCategory(this);
+        }
     }
     else if (changedField == &m_plotAxis)
     {
diff --git a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.h b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.h
index 1e0258e118..8e5305a682 100644
--- a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.h
+++ b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurve.h
@@ -80,6 +80,9 @@ public:
     void                                    forceUpdateCurveAppearanceFromCaseType();
 
     void                                    markCachedDataForPurge();
+    
+    void                                    setAsTopZWithinCategory(bool enable);
+    void                                    setZIndexFromCurveInfo();
 
 protected:
     // RimPlotCurve overrides
@@ -106,7 +109,6 @@ private:
     static void                             appendOptionItemsForSummaryAddresses(QList<caf::PdmOptionItemInfo>* options,
                                                                                  RimSummaryCase* summaryCase,
                                                                                  RimSummaryFilter* summaryFilter);
-    void                            setZIndexFromCurveInfo();
 
 private:
     // Y values
@@ -127,4 +129,5 @@ private:
 
     caf::PdmChildField<RimSummaryCurveAutoName*>        m_curveNameConfig;
     caf::PdmField<caf::AppEnum< RiaDefines::PlotAxis>>  m_plotAxis;
+    caf::PdmField<bool>                     m_isTopZWithinCategory;
 };
diff --git a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.cpp b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.cpp
index c218bb1159..221b0686f9 100644
--- a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.cpp
+++ b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.cpp
@@ -335,6 +335,26 @@ void RimSummaryCurveCollection::handleKeyPressEvent(QKeyEvent* keyEvent)
     }
 }
 
+//--------------------------------------------------------------------------------------------------
+/// 
+//--------------------------------------------------------------------------------------------------
+void RimSummaryCurveCollection::setCurveAsTopZWithinCategory(RimSummaryCurve* curve)
+{
+    for (const auto& c : m_curves)
+    {
+        if (c == curve)
+        {
+            c->setAsTopZWithinCategory(true);
+        }
+        else
+        {
+            c->setAsTopZWithinCategory(false);
+        }
+
+        c->setZIndexFromCurveInfo();
+    }
+}
+
 //--------------------------------------------------------------------------------------------------
 /// 
 //--------------------------------------------------------------------------------------------------
diff --git a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.h b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.h
index 66539de4be..b0684669ec 100644
--- a/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.h
+++ b/ApplicationCode/ProjectDataModel/Summary/RimSummaryCurveCollection.h
@@ -67,6 +67,8 @@ public:
 
     void                                    handleKeyPressEvent(QKeyEvent* keyEvent);
 
+    void                                    setCurveAsTopZWithinCategory(RimSummaryCurve* curve);
+
 private:
     caf::PdmFieldHandle*                    objectToggleField() override;
     void                            defineObjectEditorAttribute(QString uiConfigName,