Double battery Monitor

Wanted to monitor 2 battery together. my question is if any one battery reach fail safe criteria then failsafe will be applied or not.

Yes.

Do we have so many ADCs to connect 10 batteries seperately? I wonder what was the intention.

Yes. Or ESC Telemetry, PWM Fuel level, some others.

Wait! This can’t be only ADC monitors. I haven’t seen more than 3 ADCs on Flight controllers. This is mostly for CAN power modules.

Those would be “some others”.