HiĀ Folkert,
Thanks for getting in touch and excellent question!
The short answer is no, an installed calendar on one site cannot directly control the calendar of another site, even on the same network.
However, we do have a new plugin called iCal Importer that might do the trick here. It allows you to pull events from one calendar to another and import those either on a manual or scheduled basis. That would allow you to publish your events on one master site and theoretically push them to as many other sites as you would like. I think that’s worth checking out in this case.
Let me know if you have any other questions about iCal Importer or managing multiple calendars and I’d be happy to help!
Geoff