Hi all
As explained in this post
as I wanted to exclude the Multisensor from ST, in order to upgrade the firmware. I wanted to exclude it without removing it, as I didn’t want to loose all my CoRE pistons.
In the end I found out by myself that by pressing down the action button on the multisensor for 30 seconds, it got excluded and I could then start firmware upgrade process.
BUT apparently ST didn’t just exclude it, but removed it. Which means that my Pistons where the Multisensor was a trigger, is now completely empty 
So for my future firmware upgrades, does anyone know how to exclude the multisensor, without removing it?
For the firmware upgrade I have bought a zwave.me usb stick. It has no buttons.