Assuming you are talking about two hubs and one location where you have spread tasks across two hubs, then what you need is to get your devices from one hub to appear on the hub with your Google Home account.
Use either the Built-In Hub Link/Link to Hub apps, or use the community [HubConnect] (HubConnect - visualizing connectivity) app. And while I like @csteele 's visulaization of how HubConnect works, he forgot to add a link in that post to the actual HubConnect post 
