J.C.
Thank goodness everyone is okay from the car accident...I am sorry to hear that that happened. I would limit my driving, like you said, until the car seats come in. I got into a wreck last year...someone hit me. My insurance company said that they would reimburse me for all of the car seats or booster seats in my car, as it would not be safe to keep using the ones that were in the vehicle before the crash. Their reasoning is that once a car seat or booster seat is in a crash with impact, the structural integrity of it is compromised and whoever continues to ride in the same seat for any length of time is at a high risk for serious or fatal injury should another accident happen. I would use the Graco seat with the four year old until your new ones arrive.
Best of luck,
J.