Index: MessagePayloads.h
===================================================================
diff -u -rf677679e0381ee76e2370d4cd09cf13f9172a5c8 -r3a830d4b8e9fc21feccd870ae8a7f2c3b536cbd1
--- MessagePayloads.h	(.../MessagePayloads.h)	(revision f677679e0381ee76e2370d4cd09cf13f9172a5c8)
+++ MessagePayloads.h	(.../MessagePayloads.h)	(revision 3a830d4b8e9fc21feccd870ae8a7f2c3b536cbd1)
@@ -7,17 +7,17 @@
 *
 * @file    MessagePayloads.h
 *
-* @author  (last)      Raghu Kallala
-* @date    (last)      04-May-2026
+* @author  (last)      Sameer Kalliadan Poyil
+* @date    (last)      15-Jun-2026
 *
 * @author  (original)  Sean Nash
 * @date    (original)  07-Nov-2024
 *
 ***************************************************************************/
-
-#ifndef __MESSAGE_PAYLOADS_H__
-#define __MESSAGE_PAYLOADS_H__
 
+#ifndef __MESSAGE_PAYLOADS_H__
+#define __MESSAGE_PAYLOADS_H__
+
 #ifdef _TD_
 #include "TDCommon.h"
 #endif
@@ -41,11 +41,12 @@
     F32  dialRate;                                      ///< Set dialysate rate (mL/min).
     F32  ufRate;                                        ///< Set ultrafiltration rate (mL/min).
     F32  dialTemp;                                      ///< Set dialysate temperature (deg C).
-    BOOL bypassDialyzer;                                ///< Flag indicating whether bypass of dialyzer is requested.
+    U32  genDialysateState;                             ///< Requested DD gen dialysate sub-state (DD_GEND_MODE_STATE_T: 1=bypass, 2=delivery, 3=isolated UF).
     F32  acidConvFactor;                                ///< Conversion factor of acid type selected.
     F32  bicarbConvFactor;                              ///< Conversion factor of bicarbonate.
     U32  sodium;                                        ///< Set sodium being used to make dialysate.
     U32  bicarbonate;                                   ///< Set bicarbonate being used to make dialysate.
+    F32  substitutionRate;                              ///< Set HDF rate ( mL/min).
 } DIALYSATE_DELIVERY_REQ_PAYLOAD_T;
 
 /// Payload record structure for requesting pre generate dialysate.
@@ -111,4 +112,4 @@
 
 /**@}*/
 
-#endif
+#endif