How to mux 10 sensor units with 4-pin that must communicate with a single unit with 3 programmable input
You can do this with only two chips: 16-channel analog mux with 4-bit binary address input (e.g. ADG706) and 4-bit binary counter with "clear" input (e.g. 74HCT393).

One control pin is used to reset counter to 0, another to increment counter (change mux address), and the last one is used as analog input from mux.

Update

Here is the schematics. I've used whatever symbols were available in the Eagle, so the pin names are different from those in the datasheets. But the pinouts are compatible, so it should be trivial to figure out. And, of course, you can use any level-compatible inverter/nand/nor chip for IC4. Something like 100R resistors should be sufficient to protect sensor outputs while not interfering much with ADC. Oh, and don't forget to connect Vee of the muxes to the ground.