Addressing 23017/4051 using I2C Serial Interface & PROGMEM

OK then, based on what you have said and done, then you should be able to contruct a 16 bit integer with appropriate bits turned on and send it out to turn on the LEDs. I don't think there is a need to check if the status changed from last time, so eliminating all the code that does that will simplify your routine somewhat.

Good luck with your project!