Getting 4 carseats in a mini-van

I am watching a friend's children tomorrow so she can go to a job interview. I remembered, all of 30 minutes ago, that "Arpac 2" has a doctor's appointment at the same time. I just loaded four car seats ( Arpac 2's, an old one of Arpac's and two from my child care days) into my van. I learned that if I stand on my head, from the back of the van, I can use enough of my body weight to secure two car seats:) I also drew up a detailed plan of where everyone is seating in case some crazed soccer mom (God Forbid) crashes into me. I know paranoid, but I don't normally take other people's children in my van. I am sure the doctor's visit will be a "blast". I think the only one that will give me any problems is the one from my womb.