The techniques disclosed herein improve existing systems by generating a data object indicative of a defined group of users of a communication session, messages being communicated between the defined group of users, and permissions defined for the defined group of users to access content of the communication session. In response to receiving a selection of a message set including a subset of the messages of the defined group for corresponding with a non-member user who is not a member of the defined group, the system updates the first data object to include the selected message set and subsequent messages exchanged between the non-member user and a subset of the users in the defined group directed to the selected message set, and permissions defined for the additional participant to limit full access to other subsequent messages in the defined group not directed to the selected message set.