yes, you can pull right up to were the porters are, check in all your bags, and then just one of you go drop the car off in the parking lot. There are two lots, one right next to the terminal, and one accross the street, I think it's just luck of the draw which you get put in.
After parking, you could just meet up with your guests before going in the terminal. Both lots are within walking distance, would really only take a minute or two for one person to park the car. It's $10 a day, and I would bring cash, cause I have heard of the credit card machine going down sometimes in the toll booth. It's run by the port authority, not Disney.. so well, you know how non-Disney stuff goes
As far as when you return.. you pick up your bags in this big room, its super easy, color coded by stateroom number, then you have the option of tipping a porter to help you to where the car is, or hauling them all to your car yourselves. If you drove yourself, and the car is parked, it is not necessary to go to the pick up tent... you can just go straight to your car. The pick up tent is just for passengers who were dropped off at port.
Hope that makes sense. But it's super easy getting on and off the Disney ships.. its one of the big benefits of
DCL. They are so organized. They have the process down to a science. You'd think all these other lines who have been in the business for ever would figure out Disney's secret by now!
Oh yeah, just make sure who ever is dropping off the car has their PHOTO ID, they need it to get checked in on the passenger list.. otherwise, they can't get in the terminal. I saw this lady once who checked her purse with her ID in it.. they were able to get it, but man, did she look nervous.