Your request is very timely! Our developers have just finished working on the multiple admin emails feature. It will be available in the next plugin update. Until then, multiple emails can be added only through editing the database.
We are happy to inform that the feature that you requested was added in the latest update of the MotoPress Hotel Booking plugin.
Now you can set up multiple admin emails in Accommodation > Settings > Admin Emails / Email Settings. Make sure to update the plugin to its latest version (3.0.0) in order to use the new features.