Communication between HMIs

Communication between HMIs

Hello!

I have to separate HMI with Zenon Scada on it, they are connected to each other via Eth. They controll the same process from two different places (They are nearly the same project), I would like to provide data exchange between them, what possibilities do I have? How does licensing looking? I do have a possibility to do it over PLC, but I would like to avoid it. 

BR,
Jakub Gritner