Howto send information to another Home Assistant instance

We are living with 2 families in one house, both use there own home assistant environment. I want to exchange the smart meter information i recieve on my home assistant environment, with the other familie and send that to their home assistant environment. How can i do this? The instances are on a routed network and can connect to each other.

Use a common MQTT message broker to publish / subscribe information between the 2 instances