A method of managing a messaging application executed by an electronic device having a display and at least one input device, comprising: displaying a messaging user interface of the messaging application on the display, the messaging user interface 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, wherein the conversation transcript includes a plurality of messages and a plurality of message regions, each message region containing a respective message of the plurality of messages; while displaying the messaging user interface, detecting a first input on the at least one input device at a location corresponding to a first respective message in the conversation transcript, wherein the first respective message is contained in a first respective message region of the plurality of message regions; in response to detecting the first input, selecting the first respective message and displaying an indication that the first respective message has been selected; while displaying the indication that the first respective message has been selected, detecting a plurality of second inputs on the at least one input device, including one or more message composition inputs; and in response to detecting one input of the plurality of second inputs: displaying, in a second message region in the conversation transcript distinct from the first respective message region, a second message corresponding to the one or more message composition inputs; and displaying a grouping indicia that connects the first respective message region with the second message region; while displaying the grouping indicia that connects the first respective message region with the second message region, detecting a third input, and in response to detecting the third input, displaying the first respective message region and second message region overlaid on the conversation transcript, such that the first and second message region are simultaneously displayed. displaying a messaging user interface of the messaging application on the display, the messaging user interface 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, wherein the conversation transcript includes a plurality of messages and a plurality of message regions, each message region containing a respective message of the plurality of messages; while displaying the messaging user interface, detecting a first input on the at least one input device at a location corresponding to a first respective message in the conversation transcript, wherein the first respective message is contained in a first respective message region of the plurality of message regions; in response to detecting the first input, selecting the first respective message and displaying an indication that the first respective message has been selected; while displaying the indication that the first respective message has been selected, detecting a plurality of second inputs on the at least one input device, including one or more message composition inputs; and in response to detecting one input of the plurality of second inputs: displaying, in a second message region in the conversation transcript distinct from the first respective message region, a second message corresponding to the one or more message composition inputs; and displaying a grouping indicia that connects the first respective message region with the second message region; detecting a first input on the at least one input device at a location corresponding to a first respective message in the conversation transcript, wherein the first respective message is contained in a first respective message region of the plurality of message regions; in response to detecting the first input, selecting the first respective message and displaying an indication that the first respective message has been selected; while displaying the indication that the first respective message has been selected, detecting a plurality of second inputs on the at least one input device, including one or more message composition inputs; and in response to detecting one input of the plurality of second inputs: displaying, in a second message region in the conversation transcript distinct from the first respective message region, a second message corresponding to the one or more message composition inputs; and displaying a grouping indicia that connects the first respective message region with the second message region; displaying, in a second message region in the conversation transcript distinct from the first respective message region, a second message corresponding to the one or more message composition inputs; and displaying a grouping indicia that connects the first respective message region with the second message region; while displaying the grouping indicia that connects the first respective message region with the second message region, detecting a third input, and in response to detecting the third input, displaying the first respective message region and second message region overlaid on the conversation transcript, such that the first and second message region are simultaneously displayed.