Open House is a very good process to understand and improve internal and external processes and understand the loopholes in the system. It is necessary to have one representative from each department to answer the queries of the associates at the same time as the queries may be pertaining not only related to HR. Also, needs to ensure to resolve or reply all queries raised by the associates during open house as some queries may not be answered or resolved at the same time but yes you need to inform all the participents on as and when it is resolved.You need to have proper time line and followup to resolve all query and response to the people.
This is in addition of what Manoj has said.
On completion of the meeting, Minutes of Meeting (MOM) have to be circulated to all the HODs. In the MOM, you have to mention, who will take action.
When the next open house meeting takes place, you need to read out the points that were raised in the last meeting and action taken thereafter. If action on some point is still pending then it needs to be explained why the action is pending. After review of the last meeting, fresh meeting starts.
In Google, CEO shows the presentation in their meeting that he had given to the BoD. Therefore, there is no variation in what was told to BoD and the employees.
From India, Bangalore