V60 Dual-Zone to Tri-Zone Climate Control: Adding Rear Seat Air Vents?

[IMAY2023]

After retrofitting rear heated and ventilated seats I tested this to be able control rear seat heating and ventilation from the center display "Rear climate control" 
Changing the setting "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC  enables the rear climate control under the climate control main page. Option appears at the top tabs of the climate control screen. 

However, it breaks the climate system. 
CCM throws DTCs 
1) missing temp sensors on the rear floor air vents (under each front seat) 
2) missing temp sensors on the rear console air vents although 339 SECOND ROW CENTRE VENT is set to 01 without
3) missing actuators for opening and closing the floor vents. 

In addition to DTCs, 
When you change the output vents from the center display, it does not do anything. In fact, no air coming out from any vent regardless which ones you choose. 

There are 3 types of rear seat heating switch. 
1) Basic one that has only two buttons controls only heating level for each side. 
2) Digital, controls both air vent speed and heated rear seats.  This switch is turned on only when  "175 HVAC VARIANTS"  is set to 02 HVAC large 4 zone ECC. 
3) Digital, controls both air vent speed, heated and ventilated rear seats.  Do not know if it turns on without setting  "175 HVAC VARIANTS"  to 02 HVAC large 4 zone ECC.  Because I could not find a used one to buy and test it. 

At the moment, I installed the basic button "1" above so at least I can use the heated rear seats without breaking the climate control. 

Is there anyway to activate the rear climate control part on the center display without messing up the CCM. In order words, trick the CCM not to activate 4 zone while activating only on center display?

I'm working on something with some similarity, now. I am basically retrofitting my own version of the AliExpress kit; I have two 90mm case fans drawing air conditioned air through tubes from the ducting in front of the center console, and am using a factory vent with the touch screen controls. That switch uses LIN to communicate with everything else. T   he simple buttons you referenced have a different PID than the touch screen, and the HVAC variants option is what controls that. Long story long, I am working on an arduino based interceptor that will read the applicable values from the touch screen switch and relay to the car what it expects to see. I'm also using that arduino to ingest the fan settings so that I can control the speed of the fans that I retrofitted.  

Thank you for the info. 
I know, REAR CONSOLE SWITCH MODULE RCSM  is operating on LIN connection to the IHU and different types of switches uses different LIN signal to turn on/off. 
I wired the switch connector to the IHU and my both switches work if I set the corresponding configuration.  I have the digital with heated seats (not ventilated) and simple switch. 

I am not planning to retrofit rear air vents on the rear console or I don't care about controlling the fan speed, controlling the fan speed would be just nice to have bonus for the kids to play with. 
I can control the rear seat heating with the basic switch. What I do care about turning on/off the rear seat ventilation. So, either I find and use the attached panel or find a way to enable rear seat climate control on the IHU without effecting the CCM configuration.  The CCM must still think it's 2 zone climate so that it does not try to control rear vents and complain about the rear vent temp sensors.  
Can you share more details about the  arduino based interceptor?