Advanced Training and Seminar Setup using ZoomISO and Ecamm and Loopback

We host a bi-weekly training seminar with Zoom. The training requires:

• verbal participant interaction between the presenter and participants
• sharing of the presenter's screen
• continuous view of the presenter (uses a lot of expressions and hand gestures)
• spotlight between the presenter and one to three participants

The presenter is in Florida (and sometimes a second presenter is in Canada), the producer/director/tech support is in Missouri, and the participants are throughout North America. The primary presenter is not tech-savvy; therefore, everything has to be as simple as possible. 

I, the producer/director/tech support, have ecamm, ZoomISO, and Loopback on my M1 MacBook Pro. I'm unsure how I take the presenter's camera, audio, and screen share and pipe it through ecamm. I want to use an overlay and then present the output of ecamm to the participants, all while keeping the ability for everyone to communicate. I know how to pull the presenter camera and screen into ecamm using ZoomISO; what I do after that is what I'm unsure of. See attached for details and a visual representation. 

I'm not a complete noob, as I have a broadcast background learned during the analog-to-digital transition period. I've also helped take a church entirely online, designing and implementing a three-PTZ camera setup with two-way communication. What I'm trying to do here is a step above.  

Thank you for any help and guidance you can offer.