diff --git a/src/ZB.MOM.WW.ScadaBridge.Transport/Export/BundleExporter.cs b/src/ZB.MOM.WW.ScadaBridge.Transport/Export/BundleExporter.cs
index 7b079cdf..1280e063 100644
--- a/src/ZB.MOM.WW.ScadaBridge.Transport/Export/BundleExporter.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.Transport/Export/BundleExporter.cs
@@ -95,7 +95,15 @@ public sealed class BundleExporter : IBundleExporter
             DbConnections: resolved.DatabaseConnections.Count,
             NotificationLists: resolved.NotificationLists.Count,
             SmtpConfigs: resolved.SmtpConfigs.Count,
-            ApiMethods: resolved.ApiMethods.Count);
+            ApiMethods: resolved.ApiMethods.Count,
+            // M8 (B3): additive site/dataConnection/instance counts. Sourced from
+            // the serialized content DTO — the same arrays the importer reads —
+            // so the manifest summary always matches the packed payload. These
+            // arrays default to empty until B1/B2 populate them, so the counts
+            // are 0 today and become correct once those waves land.
+            Sites: contentDto.Sites.Count,
+            DataConnections: contentDto.DataConnections.Count,
+            Instances: contentDto.Instances.Count);
 
         // 4. Build a TEMPLATE manifest. BundleSerializer.Pack re-stamps both
         //    ContentHash and EncryptionMetadata against the bytes it actually
diff --git a/src/ZB.MOM.WW.ScadaBridge.Transport/Serialization/ManifestBuilder.cs b/src/ZB.MOM.WW.ScadaBridge.Transport/Serialization/ManifestBuilder.cs
index 856bbb5b..e5bbe755 100644
--- a/src/ZB.MOM.WW.ScadaBridge.Transport/Serialization/ManifestBuilder.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.Transport/Serialization/ManifestBuilder.cs
@@ -12,7 +12,12 @@ namespace ZB.MOM.WW.ScadaBridge.Transport.Serialization;
 public sealed class ManifestBuilder
 {
     public const int CurrentBundleFormatVersion = 1;
-    public const string CurrentSchemaVersion = "1.0";
+
+    // Schema minor version. Bumped 1.0 → 1.1 in M8 to carry the additive
+    // site/dataConnection/instance summary counts (and their content arrays).
+    // Minor bumps are additive-only: ManifestValidator gates solely on
+    // BundleFormatVersion, so an older "1.0" bundle still validates Ok.
+    public const string CurrentSchemaVersion = "1.1";
 
     /// <summary>
     /// Builds a <see cref="BundleManifest"/> with the current format version, a SHA-256 content hash,
diff --git a/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/ManifestBuilderTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/ManifestBuilderTests.cs
index 44ccf545..e2d98333 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/ManifestBuilderTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.Transport.Tests/Serialization/ManifestBuilderTests.cs
@@ -14,7 +14,8 @@ public sealed class ManifestBuilderTests
     public void Build_populates_summary_from_contents()
     {
         var sut = new ManifestBuilder();
-        var summary = new BundleSummary(2, 1, 0, 0, 0, 0, 0, 0);
+        // M8 (B3): summary now carries trailing Sites/DataConnections/Instances counts.
+        var summary = new BundleSummary(2, 1, 0, 0, 0, 0, 0, 0, Sites: 3, DataConnections: 4, Instances: 5);
         var contents = new[]
         {
             new ManifestContentEntry("Template", "T1", 1, Array.Empty<string>()),
@@ -25,12 +26,17 @@ public sealed class ManifestBuilderTests
         var manifest = sut.Build("env", "user", "1.0.0", encryption: null, summary, contents, contentBytes: new byte[] { 1, 2, 3 });
 
         Assert.Equal(summary, manifest.Summary);
+        // New M8 summary counts flow through the builder verbatim.
+        Assert.Equal(3, manifest.Summary.Sites);
+        Assert.Equal(4, manifest.Summary.DataConnections);
+        Assert.Equal(5, manifest.Summary.Instances);
         Assert.Equal(contents, manifest.Contents);
         Assert.Equal("env", manifest.SourceEnvironment);
         Assert.Equal("user", manifest.ExportedBy);
         Assert.Equal("1.0.0", manifest.ScadaBridgeVersion);
         Assert.Equal(1, manifest.BundleFormatVersion);
-        Assert.Equal("1.0", manifest.SchemaVersion);
+        // M8 (B3): schema minor bumped 1.0 → 1.1; format version stays 1.
+        Assert.Equal("1.1", manifest.SchemaVersion);
         Assert.Null(manifest.Encryption);
     }
 
@@ -100,4 +106,51 @@ public sealed class ManifestBuilderTests
 
         Assert.Equal(ManifestValidationResult.Ok, result);
     }
+
+    [Fact]
+    public void Validate_accepts_older_schemaVersion_1_0_manifest()
+    {
+        // An older "1.0" bundle (pre-M8) must still import: schema minor differences
+        // are additive and the validator gates only on BundleFormatVersion.
+        var bytes = Encoding.UTF8.GetBytes("legacy-bundle");
+        var hash = "sha256:" + Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
+        var manifest = new BundleManifest(
+            BundleFormatVersion: ManifestBuilder.CurrentBundleFormatVersion,
+            SchemaVersion: "1.0",
+            CreatedAtUtc: DateTimeOffset.UtcNow,
+            SourceEnvironment: "env",
+            ExportedBy: "u",
+            ScadaBridgeVersion: "v",
+            ContentHash: hash,
+            Encryption: null,
+            Summary: EmptySummary,
+            Contents: NoContents);
+
+        var result = new ManifestValidator().Validate(manifest, bytes);
+
+        Assert.Equal(ManifestValidationResult.Ok, result);
+    }
+
+    [Fact]
+    public void Validate_refuses_bundleFormatVersion_2()
+    {
+        // A future format-version 2 is a hard refusal (not a minor schema bump).
+        var bytes = Encoding.UTF8.GetBytes("future-bundle");
+        var hash = "sha256:" + Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
+        var manifest = new BundleManifest(
+            BundleFormatVersion: 2,
+            SchemaVersion: "1.1",
+            CreatedAtUtc: DateTimeOffset.UtcNow,
+            SourceEnvironment: "env",
+            ExportedBy: "u",
+            ScadaBridgeVersion: "v",
+            ContentHash: hash,
+            Encryption: null,
+            Summary: EmptySummary,
+            Contents: NoContents);
+
+        var result = new ManifestValidator().Validate(manifest, bytes);
+
+        Assert.Equal(ManifestValidationResult.UnsupportedFormatVersion, result);
+    }
 }