Control more than one openHAB installation with Alexa?

I have two openHAB installations running, one for our home devices, one for the devices in my office. I wonder how I can use Alexa to control devices in both installations? There doesn’t seem to be a way to connect more than one openHAB instance to, and there’s obviously no way to connect more than one account to the Alexa openHAB skill either.

Am I missing something? Can anyone give me a hint how to accomplish this?