An electronic device displays a messaging user interface of a message application, including a conversation transcript of a messaging session between a user of the electronic device and at least one other user, a message-input area, the conversation transcript including a plurality of messages and a plurality of message regions, each message region containing a respective message of the plurality of messages. In response to a first input corresponding to a first respective message in the conversation transcript, displaying an indication that the first respective message has been selected. In response to one or more second inputs, including message composition inputs, displaying in a second message region in the conversation transcript a second message corresponding to the message composition inputs, and displaying a grouping indicia that connects the first respective message region with the second message region.