Am I allowed to ask why? Reading through the thread the maximum voltage you are trying to measure is 12.4 volts so I could you just use two resistors in series as a potential divider with the middle point connected to an analog input. For example, a 10K resistor in series with a 3K3 resistor would give you about 3.08V at the centre tap - nice to have a bit of headroom. I don’t know the resistance looking into the I/O lines but whatever it is, the 3.08V will be a little lower. If it’s high enough you may be fine with 100K and 33K drawing less current for the same job.
Sorry if I’ve completely misunderstood your post - won’t be the first time…