The system gets a request to add a communication node to an existing peer-to-peer communication session between two communication nodes. The communication node is added to the existing peer-to-peer communication session. The communication nodes in the existing peer-to-peer communication have not previously defined a mixing node. The communication nodes in the existing peer-to-peer communication session exchange a mixing score. A mixing node is determined based on the exchanged mixing score. Additional systems are defined which determine a mixing node when two peer-to-peer communication sessions are joined into a combined peer-to-peer communication session.