My fellow zwavers,
I am Ricardo from Portugal, I have a passion for computers and aspire to make my home smarter, but since I am not an Electricioner, I’m only taking baby steps in that direction. 
I’ve hit a wall along the way, and I’m here to ask for your help getting around it. Here goes:
From what I have read, to be able to control with z-wave a 3-way switch (one light, two on-off switches like at the beginning and at the end of a staircase), you have to have a master and an auxiliary zwave device.
So here’s my first question: Is this correct? Is it absolutely necessary to have two zwave devices? A lot of money would be saved if this was not true.
But all guides I’ve read so far point to some master and some auxiliary switches sold by some brands, i.e. GE. But all of them are for the wall switches themselves, that you put on the wall, and also for US standards or something like that, and they have nothing to do with Portuguese or European switches, therefore, they don’t fit in the boxes that I have in my walls since they are kind of rectangular and here they are kinda squared.
And for a simple switch I have bought micro-modules like “Fibaro FGS-212 Switch 2,5kW - Micromodule Interrupteur On / Off”, or for some blinds or roller shutters I have an equivalent simple micro-module that fits inside the wall box and I get to keep the existing switches. These, I have managed to get them to work right out of the box.
So here’s my second question: For a 3-way switch, can you indicate a micro-module that is a “slave” or “auxiliary” like the Fibaro (or any other brand) that I can put inside the wall box and keep my existing switches?
So my last question: for the 3-way switch, and in case I have to install two micro-modules (one master, one auxiliary), can somebody explain the wiring?
Below is a picture of a 3-way switch in Portugal that might help anyone who is willing to help me understand the wiring.
Thank you a million
