Linking Remote Siren

I am using Vera as an alarm system at a business I own. I also have a Vera device at my house.

I would like to set up a siren on my home Vera device that will activate if any of the sensors are tripped on the business device.

Any idea how I link these devices online?

Hi and welcome.
There was a discussion here about this subject

Which Vera model(s) are you using? It matters in this case, because one or both may become eligible in the future for use with ezlo VOI™ (currently in testing) that could – in theory! – use Alexa or Google Home Assistant as an intermediary to trigger devices at different locations.

A work-around, yes, but very few good such approaches have proven effective, reliable or easy-to-implement. Let us know what your research turns up!