diff --git a/src/s2python/message.py b/src/s2python/message.py
index aafc009..030d8e2 100644
--- a/src/s2python/message.py
+++ b/src/s2python/message.py
@@ -1,50 +1,98 @@
 from typing import Union
 
 from s2python.frbc import (
+    FRBCActuatorDescription,
     FRBCActuatorStatus,
     FRBCFillLevelTargetProfile,
+    FRBCFillLevelTargetProfileElement,
     FRBCInstruction,
     FRBCLeakageBehaviour,
+    FRBCLeakageBehaviourElement,
+    FRBCOperationMode,
+    FRBCOperationModeElement,
+    FRBCStorageDescription,
     FRBCStorageStatus,
     FRBCSystemDescription,
     FRBCTimerStatus,
-    FRBCUsageForecast
+    FRBCUsageForecast,
+    FRBCUsageForecastElement,
 )
 from s2python.ppbc import (
+    PPBCEndInterruptionInstruction,
+    PPBCPowerProfileDefinition,
+    PPBCPowerSequenceContainer,
+    PPBCPowerSequence,
+    PPBCPowerProfileStatus,
+    PPBCPowerSequenceContainerStatus,
+    PPBCPowerSequenceElement,
     PPBCScheduleInstruction,
+    PPBCStartInterruptionInstruction,
 )
 
 from s2python.common import (
+    Duration,
     Handshake,
     HandshakeResponse,
     InstructionStatusUpdate,
+    NumberRange,
     PowerForecast,
+    PowerForecastElement,
+    PowerForecastValue,
     PowerMeasurement,
+    PowerRange,
+    PowerValue,
     ReceptionStatus,
     ResourceManagerDetails,
     RevokeObject,
+    Role,
     SelectControlType,
-    SessionRequest
+    SessionRequest,
+    Timer,
+    Transition,
 )
 
 S2Message = Union[
+    FRBCActuatorDescription,
     FRBCActuatorStatus,
     FRBCFillLevelTargetProfile,
+    FRBCFillLevelTargetProfileElement,
     FRBCInstruction,
     FRBCLeakageBehaviour,
+    FRBCLeakageBehaviourElement,
+    FRBCOperationMode,
+    FRBCOperationModeElement,
+    FRBCStorageDescription,
     FRBCStorageStatus,
     FRBCSystemDescription,
     FRBCTimerStatus,
     FRBCUsageForecast,
+    FRBCUsageForecastElement,
+    PPBCEndInterruptionInstruction,
+    PPBCPowerProfileDefinition,
+    PPBCPowerSequenceContainer,
+    PPBCPowerSequence,
+    PPBCPowerProfileStatus,
+    PPBCPowerSequenceContainerStatus,
+    PPBCPowerSequenceElement,
     PPBCScheduleInstruction,
+    PPBCStartInterruptionInstruction,
+    Duration,
     Handshake,
     HandshakeResponse,
     InstructionStatusUpdate,
+    NumberRange,
     PowerForecast,
+    PowerForecastElement,
+    PowerForecastValue,
     PowerMeasurement,
+    PowerRange,
+    PowerValue,
     ReceptionStatus,
     ResourceManagerDetails,
     RevokeObject,
+    Role,
     SelectControlType,
     SessionRequest,
+    Timer,
+    Transition,
 ]
diff --git a/src/s2python/ppbc/__init__.py b/src/s2python/ppbc/__init__.py
index 1e0b4d3..f38ad46 100644
--- a/src/s2python/ppbc/__init__.py
+++ b/src/s2python/ppbc/__init__.py
@@ -10,3 +10,4 @@
     PPBCPowerSequenceContainerStatus,
 )
 from s2python.ppbc.ppbc_power_sequence_element import PPBCPowerSequenceElement
+from s2python.ppbc.ppbc_start_interruption_instruction import PPBCStartInterruptionInstruction
diff --git a/tests/unit/message_test.py b/tests/unit/message_test.py
new file mode 100644
index 0000000..06e2798
--- /dev/null
+++ b/tests/unit/message_test.py
@@ -0,0 +1,56 @@
+import unittest
+
+import importlib
+import inspect
+import pkgutil
+
+from s2python import message
+from s2python.validate_values_mixin import S2MessageComponent
+
+
+class S2MessageTest(unittest.TestCase):
+    """Check importing S2Message classes from s2_python.message."""
+
+    def _test_import_s2_messages(self, module_name):
+        """Check each S2MessageComponent subclass in the given module is importable."""
+        module = importlib.import_module(module_name)
+
+        # Find all submodules
+        all_subclasses = []
+        for _, name, _ in pkgutil.iter_modules(module.__path__, module.__name__ + "."):
+            submodule = importlib.import_module(name)
+
+            # Find all classes in the submodule that subclass BaseClass
+            subclasses = [
+                obj
+                for _, obj in inspect.getmembers(submodule, inspect.isclass)
+                if issubclass(obj, S2MessageComponent) and obj is not S2MessageComponent
+            ]
+            all_subclasses.extend(subclasses)
+
+        # Ensure we found at least one subclass
+        self.assertGreater(
+            len(all_subclasses), 0, f"No subclasses found in {module_name}"
+        )
+
+        for _class in all_subclasses:
+            assert hasattr(
+                message, _class.__name__
+            ), f"{_class} should be importable from s2_python.message"
+
+    def test_import_s2_messages__common(self):
+        self._test_import_s2_messages("s2python.common")
+
+    @unittest.skip("Work in progress")
+    def test_import_s2_messages__ddbc(self):
+        self._test_import_s2_messages("s2python.ddbc")
+
+    def test_import_s2_messages__frbc(self):
+        self._test_import_s2_messages("s2python.frbc")
+
+    @unittest.skip("Work in progress")
+    def test_import_s2_messages__pebc(self):
+        self._test_import_s2_messages("s2python.pebc")
+
+    def test_import_s2_messages__ppbc(self):
+        self._test_import_s2_messages("s2python.ppbc")