Index: firmware/App/Services/Messaging.c
===================================================================
diff -u -r5f1b50a1d9a7bd6ea17bb666e28ccfeafe56432c -r84b54a6a2e4478c49853f461b8e1ba560441f147
--- firmware/App/Services/Messaging.c	(.../Messaging.c)	(revision 5f1b50a1d9a7bd6ea17bb666e28ccfeafe56432c)
+++ firmware/App/Services/Messaging.c	(.../Messaging.c)	(revision 84b54a6a2e4478c49853f461b8e1ba560441f147)
@@ -7,8 +7,8 @@
 *
 * @file    Messaging.c
 *
-* @author  (last)      Dara Navaei
-* @date    (last)      27-May-2026
+* @author  (last)      Michael Garthwaite
+* @date    (last)      11-Jun-2026
 *
 * @author  (original)  Vinayakam Mani
 * @date    (original)  07-Aug-2024
@@ -38,6 +38,7 @@
 #include "Level.h"
 #include "Messaging.h"
 #include "MessagePayloads.h"
+#include "MixingControl.h"
 #include "ModeGenDialysate.h"
 #include "ModeGenPermeate.h"
 #include "ModeGenPermeateDefeatured.h"
@@ -59,6 +60,7 @@
 #include "StateFlushFilterDefeatured.h"
 #include "StateFlushPermeate.h"
 #include "StateInletPressureCheck.h"
+#include "SubstitutionPump.h"
 #include "SystemCommDD.h"
 #include "Temperature.h"
 #include "TestSupport.h"
@@ -277,10 +279,10 @@
     { MSG_ID_FP_DEF_PRE_GEN_PUBLISH_INTERVAL_OVERRIDE_REQUEST,                      &testPreGenPermeateDefDataPublishIntervalOverride},
     { MSG_ID_FP_DEF_GEN_PUBLISH_INTERVAL_OVERRIDE_REQUEST,                          &testGenPermeateDefDataPublishIntervalOverride},
     { MSG_ID_FP_DEF_STATUS_REQUEST,                                                 &testGetFPDefeaturedStatus },
-    { MSG_ID_DD_BICARB_MIX_VOL_CONTROL_KP_GAIN_COEFF_OVERRIDE_REQUEST,              &testDryBiCartBicarbMixVolControlKiGainOverride },
-    { MSG_ID_DD_BICARB_MIX_VOL_CONTROL_KI_GAIN_COEFF_OVERRIDE_REQUEST,              &testDryBiCartAcidMixVolControlKpGainOverride },
-    { MSG_ID_DD_ACID_MIX_VOL_CONTROL_KP_GAIN_COEFF_OVERRIDE_REQUEST,                &testDryBiCartAcidMixVolControlKpGainOverride },
-    { MSG_ID_DD_ACID_MIX_VOL_CONTROL_KI_GAIN_COEFF_OVERRIDE_REQUEST,                &testDryBiCartAcidMixVolControlKiGainOverride },
+    { MSG_ID_DD_BICARB_MIX_VOL_CONTROL_KP_GAIN_COEFF_OVERRIDE_REQUEST,              &testMixingControlBicarbVolControlKiGainOverride },
+    { MSG_ID_DD_BICARB_MIX_VOL_CONTROL_KI_GAIN_COEFF_OVERRIDE_REQUEST,              &testMixingControlBicarbVolControlKpGainOverride },
+    { MSG_ID_DD_ACID_MIX_VOL_CONTROL_KP_GAIN_COEFF_OVERRIDE_REQUEST,                &testMixingControlAcidVolControlKpGainOverride },
+    { MSG_ID_DD_ACID_MIX_VOL_CONTROL_KI_GAIN_COEFF_OVERRIDE_REQUEST,                &testMixingControlAcidVolControlKiGainOverride },
     { MSG_ID_DD_BICART_UPPER_PRESSURE_OVERRIDE_REQUEST,                             &testDryBiCartUpperCartPressureOverride },
     { MSG_ID_DD_BICART_LOWER_PRESSURE_OVERRIDE_REQUEST,                             &testDryBiCartLowerCartPressureOverride } ,
     { MSG_ID_FP_SET_OPERATION_SUB_MODE_REQUEST,                                     &testSetFPOperationSubMode },
@@ -290,6 +292,9 @@
     { MSG_ID_FP_CONDUCTIVITY_SENSOR_VERSION_REQUEST,                                &testHandleConductivitySensorVersionRequest },
     { MSG_ID_DD_TEMPERATURE_SENSOR_FILTERED_TEMP_OVERRIDE_REQUEST,                  &testDDTemperatureSensorFilteredReadingsOverride },
     { MSG_ID_FP_SET_RECOVERY_VALVES_REQUEST,                                        &testIOFPSetValveRecoveryConfig },
+    { MSG_ID_DD_SUBSTITUTION_PUMP_START_STOP_OVERRIDE_REQUEST,                      &testSubstitutionPumpStartStopOverride },
+    { MSG_ID_DD_SUBSTITUTION_PUMP_BROADCAST_INTERVAL_OVERRIDE_REQUEST,              &testSubstitutionPumpDataPublishIntervalOverride },
+    { MSG_ID_DD_SUBSTITUTION_PUMP_TARGET_RATE_OVERRIDE_REQUEST,                    &testSubstitutionPumpTargetRateOverride },
 };
 
 /// Calculation for number of entries in the incoming message function handler look-up table.