diff --git a/RcbExportFilterWindow.VirtualizedSelectionAuthority.cs b/RcbExportFilterWindow.VirtualizedSelectionAuthority.cs
new file mode 100644
index 000000000..26520deb4
--- /dev/null
+++ b/RcbExportFilterWindow.VirtualizedSelectionAuthority.cs
@@ -0,0 +1,53 @@
+using System.Runtime.CompilerServices;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
+using ArIED61850Tester.Models;
+
+namespace ArIED61850Tester;
+
+/// <summary>
+/// Keeps the P1 multi-RCB selection model authoritative when the legacy DataGrid virtualizes
+/// and recycles checkbox containers. A recycled CheckBox re-applies IsChecked from the bound
+/// RcbExportRow.IsSelected value, which raises Checked/Unchecked even though the operator did
+/// not change selection. The original single-select instance handlers interpret that visual
+/// rehydration as a user action and call SelectOnly, silently clearing the other selected RCBs.
+///
+/// P1 pointer/keyboard handling already owns real operator selection changes, so these routed
+/// state-change events are presentation-only for this grid and must not reach the stale
+/// single-select handlers.
+/// </summary>
+public partial class RcbExportFilterWindow
+{
+    [ModuleInitializer]
+    internal static void RegisterLegacyRcbVirtualizedSelectionAuthority()
+    {
+        EventManager.RegisterClassHandler(
+            typeof(CheckBox),
+            ToggleButton.CheckedEvent,
+            new RoutedEventHandler(SuppressLegacyRcbSingleSelectStateHandler),
+            handledEventsToo: true);
+        EventManager.RegisterClassHandler(
+            typeof(CheckBox),
+            ToggleButton.UncheckedEvent,
+            new RoutedEventHandler(SuppressLegacyRcbSingleSelectStateHandler),
+            handledEventsToo: true);
+    }
+
+    private static void SuppressLegacyRcbSingleSelectStateHandler(object sender, RoutedEventArgs e)
+    {
+        if (sender is not CheckBox checkBox ||
+            checkBox.DataContext is not RcbExportRow ||
+            Window.GetWindow(checkBox) is not RcbExportFilterWindow window ||
+            FindP1LegacyRcbAncestor<DataGrid>(checkBox) is not { } grid ||
+            !ReferenceEquals(grid, window.RcbGrid))
+        {
+            return;
+        }
+
+        // Do not allow the original XAML Checked/Unchecked instance handlers to translate
+        // DataGrid container materialization/recycling into a single-selection mutation.
+        // RcbExportRow.IsSelected remains the durable selection authority.
+        e.Handled = true;
+    }
+}
diff --git a/tests/ARSAS.Tests/RcbSelectionVirtualizationRegressionTests.cs b/tests/ARSAS.Tests/RcbSelectionVirtualizationRegressionTests.cs
new file mode 100644
index 000000000..f88878589
--- /dev/null
+++ b/tests/ARSAS.Tests/RcbSelectionVirtualizationRegressionTests.cs
@@ -0,0 +1,81 @@
+using ArIED61850Tester;
+using ArIED61850Tester.Models;
+
+namespace ARSAS.Tests;
+
+public sealed class RcbSelectionVirtualizationRegressionTests
+{
+    [Fact]
+    public void LegacyRcbGrid_RecycledCheckboxEventsCannotReachSingleSelectHandlers()
+    {
+        var xaml = Read("RcbExportFilterWindow.xaml");
+        var authority = Read("RcbExportFilterWindow.VirtualizedSelectionAuthority.cs");
+
+        Assert.Contains(
+            "IsChecked=\"{Binding IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}\"",
+            xaml,
+            StringComparison.Ordinal);
+
+        // These legacy handlers still exist for the original single-RCB window contract. The
+        // P1 multi-select authority must stop virtualization-generated Checked/Unchecked events
+        // before those instance handlers can translate visual rehydration into SelectOnly().
+        Assert.Contains("Checked=\"RcbCheckBox_Checked\"", xaml, StringComparison.Ordinal);
+        Assert.Contains("Unchecked=\"RcbCheckBox_Unchecked\"", xaml, StringComparison.Ordinal);
+        Assert.Contains("ToggleButton.CheckedEvent", authority, StringComparison.Ordinal);
+        Assert.Contains("ToggleButton.UncheckedEvent", authority, StringComparison.Ordinal);
+        Assert.Contains("ReferenceEquals(grid, window.RcbGrid)", authority, StringComparison.Ordinal);
+        Assert.Contains("e.Handled = true", authority, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void MultiRcbSelectionAuthority_KeepsIndependentRowsSelected()
+    {
+        var rows = new List<RcbExportRow>
+        {
+            NewRow("Buffer"),
+            NewRow("Unbuffer"),
+            NewRow("A_URCB"),
+            NewRow("A_URCB_1"),
+            NewRow("A_URCB_10")
+        };
+        var anchorIndex = -1;
+        var anchorValue = false;
+
+        for (var index = 0; index < 4; index++)
+        {
+            MainWindow.ApplyRcbSelectionForTest(
+                rows,
+                ref anchorIndex,
+                ref anchorValue,
+                index,
+                extendRange: false);
+        }
+
+        Assert.Equal(4, rows.Count(row => row.IsSelected));
+        Assert.All(rows.Take(4), row => Assert.True(row.IsSelected));
+        Assert.False(rows[4].IsSelected);
+    }
+
+    private static RcbExportRow NewRow(string name)
+        => new()
+        {
+            Name = name,
+            Reference = $"IED/LLN0.{name}",
+            SourceSelectionKey = name,
+            ExportName = name
+        };
+
+    private static string Read(string relativePath)
+    {
+        DirectoryInfo? directory = new(AppContext.BaseDirectory);
+        while (directory != null)
+        {
+            var candidate = Path.Combine(directory.FullName, relativePath);
+            if (File.Exists(candidate))
+                return File.ReadAllText(candidate);
+            directory = directory.Parent;
+        }
+
+        throw new FileNotFoundException(relativePath);
+    }
+}