diff --git a/src/item.cpp b/src/item.cpp
index ec0ad630d2..471dff1eae 100644
--- a/src/item.cpp
+++ b/src/item.cpp
@@ -245,24 +245,6 @@ void Item::stackAfter(Item *sibling)
     sibling->scheduleRepaint(sibling->boundingRect());
 }
 
-void Item::stackChildren(const QList<Item *> &children)
-{
-    if (m_childItems.count() != children.count()) {
-        qCWarning(KWIN_CORE) << Q_FUNC_INFO << "invalid child list";
-        return;
-    }
-
-#if !defined(QT_NO_DEBUG)
-    for (const Item *item : children) {
-        Q_ASSERT_X(item->parentItem() == this, Q_FUNC_INFO, "invalid parent");
-    }
-#endif
-
-    m_childItems = children;
-    discardQuads();
-    markSortedChildItemsDirty();
-}
-
 void Item::scheduleRepaint(const QRegion &region)
 {
     if (isVisible()) {
diff --git a/src/item.h b/src/item.h
index e066f40836..e9a5bbc251 100644
--- a/src/item.h
+++ b/src/item.h
@@ -73,11 +73,6 @@ public:
      * Moves this item right after the specified @a sibling in the parent's children list.
      */
     void stackAfter(Item *sibling);
-    /**
-     * Restacks the child items in the specified order. Note that the specified stacking order
-     * must be a permutation of childItems().
-     */
-    void stackChildren(const QList<Item *> &children);
 
     bool isVisible() const;
     void setVisible(bool visible);
diff --git a/src/surfaceitem_wayland.cpp b/src/surfaceitem_wayland.cpp
index e2d848bc98..fe6a29cd28 100644
--- a/src/surfaceitem_wayland.cpp
+++ b/src/surfaceitem_wayland.cpp
@@ -36,8 +36,6 @@ SurfaceItemWayland::SurfaceItemWayland(KWaylandServer::SurfaceInterface *surface
             this, &SurfaceItemWayland::handleSurfaceCommitted);
     connect(surface, &KWaylandServer::SurfaceInterface::damaged,
             this, &SurfaceItemWayland::addDamage);
-    connect(surface, &KWaylandServer::SurfaceInterface::childSubSurfaceAdded,
-            this, &SurfaceItemWayland::handleChildSubSurfaceAdded);
     connect(surface, &KWaylandServer::SurfaceInterface::childSubSurfaceRemoved,
             this, &SurfaceItemWayland::handleChildSubSurfaceRemoved);
 
@@ -48,16 +46,7 @@ SurfaceItemWayland::SurfaceItemWayland(KWaylandServer::SurfaceInterface *surface
         setPosition(subsurface->position());
     }
 
-    const QList<KWaylandServer::SubSurfaceInterface *> below = surface->below();
-    for (KWaylandServer::SubSurfaceInterface *subsurface : below) {
-        handleChildSubSurfaceAdded(subsurface);
-    }
-
-    const QList<KWaylandServer::SubSurfaceInterface *> above = surface->above();
-    for (KWaylandServer::SubSurfaceInterface *subsurface : above) {
-        handleChildSubSurfaceAdded(subsurface);
-    }
-
+    handleChildSubSurfacesChanged();
     setSize(surface->size());
 }
 
@@ -99,13 +88,15 @@ void SurfaceItemWayland::handleSurfaceCommitted()
     }
 }
 
-void SurfaceItemWayland::handleChildSubSurfaceAdded(KWaylandServer::SubSurfaceInterface *child)
+SurfaceItemWayland *SurfaceItemWayland::getOrCreateSubSurfaceItem(KWaylandServer::SubSurfaceInterface *child)
 {
-    SurfaceItemWayland *subsurfaceItem = new SurfaceItemWayland(child->surface(), window());
-    subsurfaceItem->setParent(this);
-    subsurfaceItem->setParentItem(this);
-
-    m_subsurfaces.insert(child, subsurfaceItem);
+    SurfaceItemWayland *&item = m_subsurfaces[child];
+    if (!item) {
+        item = new SurfaceItemWayland(child->surface(), window());
+        item->setParent(this);
+        item->setParentItem(this);
+    }
+    return item;
 }
 
 void SurfaceItemWayland::handleChildSubSurfaceRemoved(KWaylandServer::SubSurfaceInterface *child)
@@ -118,17 +109,15 @@ void SurfaceItemWayland::handleChildSubSurfacesChanged()
     const QList<KWaylandServer::SubSurfaceInterface *> below = m_surface->below();
     const QList<KWaylandServer::SubSurfaceInterface *> above = m_surface->above();
 
-    QList<Item *> items;
-    items.reserve(below.count() + above.count());
-
-    for (KWaylandServer::SubSurfaceInterface *subsurface : below) {
-        items.append(m_subsurfaces[subsurface]);
+    for (int i = 0; i < below.count(); ++i) {
+        SurfaceItemWayland *subsurfaceItem = getOrCreateSubSurfaceItem(below[i]);
+        subsurfaceItem->setZ(i - below.count());
     }
-    for (KWaylandServer::SubSurfaceInterface *subsurface : above) {
-        items.append(m_subsurfaces[subsurface]);
+ 
+    for (int i = 0; i < above.count(); ++i) {
+        SurfaceItemWayland *subsurfaceItem = getOrCreateSubSurfaceItem(above[i]);
+        subsurfaceItem->setZ(i);
     }
-
-    stackChildren(items);
 }
 
 void SurfaceItemWayland::handleSubSurfacePositionChanged()
diff --git a/src/surfaceitem_wayland.h b/src/surfaceitem_wayland.h
index 762c3a0156..de18775901 100644
--- a/src/surfaceitem_wayland.h
+++ b/src/surfaceitem_wayland.h
@@ -39,7 +39,6 @@ private Q_SLOTS:
     void handleSurfaceCommitted();
     void handleSurfaceSizeChanged();
 
-    void handleChildSubSurfaceAdded(KWaylandServer::SubSurfaceInterface *child);
     void handleChildSubSurfaceRemoved(KWaylandServer::SubSurfaceInterface *child);
     void handleChildSubSurfacesChanged();
     void handleSubSurfacePositionChanged();
@@ -48,6 +47,8 @@ protected:
     SurfacePixmap *createPixmap() override;
 
 private:
+    SurfaceItemWayland *getOrCreateSubSurfaceItem(KWaylandServer::SubSurfaceInterface *s);
+
     QPointer<KWaylandServer::SurfaceInterface> m_surface;
     QHash<KWaylandServer::SubSurfaceInterface *, SurfaceItemWayland *> m_subsurfaces;
 };