M.B.
I have a blazer and what we did was put the infant seat in the middle and then when the baby grew out of her seat we put the older child in a booster and the youngest on in a convertable seat. Good luck and congratulations! And we had 3 children then when the youngest was 9 found out that we were pg again! Holy cow!! She is now 4 and the 10 year old is 14 so you can do it !!!