communication script between bro instances

Hi;
I have installed and configured two instances of bro on two different LAN.
each instance monitors a LAN on which it is deployed.

Now, i want to share some events between these instances.
I would like to know what kind of events i can share between them.
Could you give me an exemple of script to share important events?
What kind of events can i consider as important to share?

thanks for your response.