Hi folks. I have one of these ESP8266 relays: 4 channel Relay ESP8266 Wifi board WORKING with esphome which is supported in esphome.
I want to control a ERV that has a bypass switch, and 3 lines (slow, med, fast ) speeds, but it’s very important that only 1 of the speed lines is selected - if two are activated at once, it can burn out the ERV control board. The bypass control line is easy to support, but I am trying to avoid depending on the interlock function since the consequences are high. 
Here is a pic of how I am thinking of wiring the 3 relays to support a hardware approach to preventing multiple lines being turned on:
The question is how do I program this into a switch that has “off”, “slow”, “medium”, and “fast” values, especially given how the serial port controlled switch works.
I appreciate the help!