Hi there and thank you for your help. The answers came later than I expected (never mind) and during a period as I am away from my arduinos and raspberry.
I will try to make a sketch to show you the set up. But I am not interested to connect the sensor directly to raspberry pi by one-wire. The set up is like this
Arduino with Dallas Temperature <> Serial interface <Serial cable> Moxa Serial to IP <Ethernet / virtual serial port> Raspberry pi as gateway with virtual serial port <Ethernet> Home assistant
I will try to use SoftwareSerial, which is what I used already without mysensors on pin 00 et 1. What I am struggling with is the mysensors configuration for serial port and the gateway on raspberry with the virtual serial port.
Keep you updated.