A method, device and system are provided for automated updating of message recipients designated for a reply message based on a declaration or notification in a body of the message. Once a reply message is initiated at a first device and an initial recipient set defined for the reply message based on the participants of a previous message of the thread, a declaration or instruction may be inserted in the message body identifying a change to be made to the initial recipient set. In response to a trigger detected at the device, any such declarations are identified and a determination is made whether the current recipient set is consistent with them. If not, changes are made to the current recipient set to render it consistent.