In my experience the certificate works the same way that a regular club room would in that you only get 2 people (adults or children) per room and have to pay extra for anyone, including children, above 2 people. Seems like there is no standard upcharge fee, it's up to each property Some properties charge less for extra children (i assume because children eat less and don't drink alcohol), but some don't. I would call to confirm pricing and reserve spots before arrival as some club lounges are capacity controlled.