I really thought that this was talked about in some capacity before but I couldn't find it with a search.
DH and I will be flying with the kids this summer. Everyone will have their own seat and will be in their own carseat. That means that we'll have three kids, three carseats, and luggage for five. This sounds like a nightmare but less of a nightmare than loosing 2 - 4 days to drive this distance.
Do any of the various carseat carriers work?
Britax Car Seat Travel Cart
Traveling Toddler Car Seat Travel Accessory (we could probably jury rig this ourselves)
Britax Car Seat Travel Bag
We also have a double stroller and might be able to use that to push two of the carseats. I plan to wear the baby and the other two are pretty good at holding hands.