I think that’s a good idea. You really need to open up the box, pull the switches out, and look behind to see what is there. 3-ways, requires opening up multiple boxes. Having a meter is a good idea for three way switches to sort out where the power originates from. Regardless you want to do the wiring well and to code, faulty wiring is the #1 cause of house fires. It’s not a skill anyone is born with. Pulling wires through an existing closed wall is difficult sometimes it’s easier to cut out the old box and put in an old construction one. Or call an electrician to do the first couple.
I looked into this but unfortunately did not find any ZigBee solution for non momentary switches 
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All of the switches shown in that diagram are momentary switches.
Yes exactly, but I don’t have those in my house…
You can change the mechanisms in any switch plate, at least you can in Australia.
Yeah I know but in many rooms I have a connection like this:
And I can not simply change them all into momentary switches I think. I have to think about it a bit more in detail.
Yes you can.
You use the traveller wires between switches to connect push button switches in parallel for the Wiser puck or for the Wiser mechanism there are control link remote mechanisms: https://www.clipsal.com/products/power-points-switches/clipsal-iconic/controllink-remote-switch-mechanism-momentary-push-button-41epbm?tab-document-1=0&itemno=41EPBM-VW
Puck (you would have 3 push buttons in parallel):
Control-link:
I went on investigating and I think it is possible with a little rewiring! And I can easily modify my switches into momentary ones (a little spring on the side)!
THANK YOU for the push in the right direction!!!
Is there a ready why you choses the wiser dimmers? A local store advised the SR-ZG9080A, have you considered those what you made your choice? I more convinced by the wiser for the moment but I still have to dig deeper!
Additional point, have you had any issue with LED loads? Have you installed any bypass or LCD device in parallel of your load? Did you change the wiser mode to rl_led?
Thank you again for the great advice!!!
I went with Clipsal Wiser as I thought they would be a premium brand without issues. Turns out they are re-branded Tuya trash simply sold at a premium price.
I went with pucks instead of switch mechanisms as I have architrave switches in most places. Putting the pucks in the roof was the best solution. The dimmer pucks only come in two wire (no neutral) versions.
The two wire dimmer pucks are terrible and randomly flicker even with Clipsal’s own LED down-lights if set to anything other than 100%.
The 3-wire dimmer mechanisms do not suffer this issue.
Fortunately all the rooms I dim the lights in the most - my lounge room, dining room and master bedroom - all have normal wall plates and I have changed to the switch mech with neutral in those locations. The electricians replaced them for free (the pucks were deemed defective).
When turning on an LED light at anything other than 100% the puck dimmers also tend to overshoot and then dim down to the required level.
I had one dimmer that could not be switched out of Bluetooth mode. The state rep had to use a previous version of their app (no longer available) to update the dimmer before it would behave correctly.
I have one dimmer that is slow to react due to interference issues as I chose a poor zigbee channel and this dimmer is right near a wifi access point on the worst possible interfering channel. I will be changing Zigbee channels soon which should fix this.
Other than that they have been rock solid on the zigbee network. Easy to update with Z2M too.
For the whole discussion I thought you were using Schneider Wiser modules (CCT5010-0002W). Never heard of Clipsal.
Ok, if I understand you ended up abandoning the pucks and using wall plate mechanism with neutral.
Ok I am starting over then, need to find pucks with three wires 
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Clipsal is what Schneider is called in Australia.
Ok didn’t know their products were not that good. I was also orbiting toward their wiser universe…
I’ll stay with nod-on and still search for good dimmers…
The mechanism dimmers (with neutral) are fine, it’s just that they are not worth the premium price.
After what you said I have the impression that they are the only option if the two wires flicker
There are other zigbee three wire options. e.g. I may still try this in the areas I have architrave switches:
Have you tried using a bypass such: Sunricher - Bypass pour lumières LED ?
Yeah. Clipsal/Schnider call them LCDs (load correction devices). Made no difference to the random flickering.