Radiator Springs Racers Ride Swap?

I'm headed to DCA tomorrow with a party that includes a 1 1/2 yr old. We all want to go on Racers, but someone has to stay off to watch the baby. I know DLR used to have a Baby Swap, and saw in the latest blog update mention of a "Ride Swap" podium where the Racers FastPass permanent location is. Anyone know how this feature works? When we swap, will only that rider who stayed off get to ride, or can the whole party (except the person now staying off with the baby) get to go?

Thanks!
Matt