In an alternative case, the broadcast group may be defined by the user of another client device, such as one of recipient devices 825. The sender device 820 may have received a group message from another client device, such as one of the recipient devices 825. The sender device 820 may have presented the group message to the user of the sender device 820 and received a response to the group message from the user for transmission to the group. As such, in some cases, the broadcast group definition 870 may be specified by the user responding to a group message in which they were included or otherwise may have been initially determined by a user of another client device.
In one embodiment, the broadcast group may be defined by the messaging system 750 to include the user client device 605 and one or more agent client devices authorized to access the message thread with the user client device 605. In some cases, this may comprise every agent client device for the multi-agent entity. The messaging system 750 may provide a list of agent client devices to the sender device 820, with the sender device 820 then instantiating the broadcast group definition 870 based on the list of agent client devices. The membership in the broadcast group may be updated, with the sender device 820 providing encryption keys to added agent client devices when requested to do so. For example, a recipient device may be added when a non-default agent client device is added in response to a non-default agent being assigned or otherwise authorize to access the message thread with a user.