diff --git a/flaml/autogen/agentchat/responsive_agent.py b/flaml/autogen/agentchat/responsive_agent.py
index 0884b88913..0305068fe3 100644
--- a/flaml/autogen/agentchat/responsive_agent.py
+++ b/flaml/autogen/agentchat/responsive_agent.py
@@ -253,7 +253,9 @@ def _message_to_dict(message: Union[Dict, str]):
         else:
             return message
 
-    def _append_oai_message(self, message: Union[Dict, str], role, conversation_id: Agent) -> bool:
+    def _append_oai_message(
+        self, message: Union[Dict, str], conversation_id: Agent, role: Optional[str] = None
+    ) -> bool:
         """Append a message to the ChatCompletion conversation.
 
         If the message received is a string, it will be put in the "content" field of the new dictionary.
@@ -262,7 +264,7 @@ def _append_oai_message(self, message: Union[Dict, str], role, conversation_id:
 
         Args:
             message (dict or str): message to be appended to the ChatCompletion conversation.
-            role (str): role of the message, can be "assistant" or "function".
+            role (str): role of the message. It can be "assistant", "user" or "function". It will be used to overwrite the "role" in the message only when original role is not "function".
             conversation_id (Agent): id of the conversation, should be the recipient or sender.
 
         Returns:
@@ -270,11 +272,17 @@ def _append_oai_message(self, message: Union[Dict, str], role, conversation_id:
         """
         message = self._message_to_dict(message)
         # create oai message to be appended to the oai conversation that can be passed to oai directly.
-        oai_message = {k: message[k] for k in ("content", "function_call", "name", "context") if k in message}
-        if "content" not in oai_message and "function_call" not in oai_message:
+        oai_message = {k: message[k] for k in ("content", "function_call", "name", "role", "context") if k in message}
+        # 'content' is a required field
+        if "content" not in oai_message:
+            return False
+        if role is not None:
+            # cannot overwrite the role if the original role is "function"
+            oai_message["role"] = role if oai_message.get("role", "") != "function" else "function"
+        elif oai_message.get("role", "") not in ("assistant", "user", "function", "system"):
+            # role is None and oai_message["role"] is not valid.
             return False
 
-        oai_message["role"] = "function" if message.get("role") == "function" else role
         self._oai_messages[conversation_id].append(oai_message)
         return True
 
@@ -319,7 +327,7 @@ def send(
         """
         # When the agent composes and sends the message, the role of the message is "assistant"
         # unless it's "function".
-        valid = self._append_oai_message(message, "assistant", recipient)
+        valid = self._append_oai_message(message, recipient, role="assistant")
         if valid:
             recipient.receive(message, self, request_reply, silent)
         else:
@@ -368,7 +376,7 @@ async def a_send(
         """
         # When the agent composes and sends the message, the role of the message is "assistant"
         # unless it's "function".
-        valid = self._append_oai_message(message, "assistant", recipient)
+        valid = self._append_oai_message(message, recipient, role="assistant")
         if valid:
             await recipient.a_receive(message, self, request_reply, silent)
         else:
@@ -409,7 +417,7 @@ def _print_received_message(self, message: Union[Dict, str], sender: Agent):
     def _process_received_message(self, message, sender, silent):
         message = self._message_to_dict(message)
         # When the agent receives a message, the role of the message is "user". (If 'role' exists and is 'function', it will remain unchanged.)
-        valid = self._append_oai_message(message, "user", sender)
+        valid = self._append_oai_message(message, sender, role="user")
         if not valid:
             raise ValueError(
                 "Received message can't be converted into a valid ChatCompletion message. Either content or function_call must be provided."