M.D.
I had a Mazda 6 wagon when I found out number 3 was on the way. We made it work for a year, and then got a Nissan Armada. HOLY HEAVEN!! The space was amazing, the fussing stopped, everyone could breathe, very worth it. I would honestly consider getting a bigger car.
Even if the older ones are in boosters, those take so much more room than just a body.