Different 3D tele-immersive (3DTI) activities pose different requirements for application and network level quality of service (QoS) to ensure a strong quality of experience (QoE) for participants. Some applications put heavy weight on audio quality, some consider higher quality for upper body video streams, and some seek very low end-to-end interactivity delay. In addition, a variation in streaming content may arise due to the participants' change of interests (e.g., view change). Therefore, there is a need for an adaptive multi-stream, multi-site 3DTI session management strategy, which is unobtrusive, and optimizes QoS parameters in the 3DTI content distribution based on the user activity and content variation. To address this next generation session management problem, we revisit the design space of multi-stream and multi-site 3DTI session layer. We propose an evolutionary 3DTI session optimization approach using an Open Session Management (OSM) architecture that uses a global view of participants and overlay network conditions to optimize prioritized QoS parameters. Experimental results with PlanetLab traces show that the optimization process is computationally unobtrusive, and the optimized TI sessions meet expectations of the participants up to 50% higher compared to the current solutions in the 3DTI space.