@serge-cherpy the only way to do this would be to set up a pi as a master and the rest as slaves…ie
one pi running your main mirror at [for example] 192.168.1.2:8080 [master]
Then running another pi and opening up a browser to 192.168.1.2:8080 [slave]
Is one way to do it. I don’t do it that way because all my mirrors do different things and have different purposes.
Bathroom mirror is an actual mirror
alarm clock mirror is a 10" touch panel that functions as an alarm clock
32" inch mirror is a home automation mirror
But the above method master->slave would work providing you have them all on the same network… if you wanted to run master on one network and the slave on another that would take more work :)