Voltage divider with MOSFETS
If you make a chain of resistors, e.g: GND - 300R - 302R - 820R - 8.9K - EXBAT_IN
then intermediate points will be at the same ratios as in your schematics.
Then you can use FETs to connect AIN0 to these intermediate points and there will be no danger of exceeding ADC voltage max (since when all FETs are OFF nothing is connected to ADC).

Another option is to remove Q2 and wire R31 to ground permanently.
Then re-calculate R32, R33 for parallel connection with R31. Not only you will protect AIN0 from overvoltage, but you will save one control line.