I now use a a travel system type stroller that also can be used as an enclosed carseat for my girls and they both fit in it perfectly plus I dont have to worry about them trying to get out of the carseat because it zips closed. Chloe was always trying to monkey around in her booster carseat and it made me sooooo nervous and I think impaired my driving skills since I had to keep calming her down (if she had things her way she really wants to be in my lap as she is such a momma's girl
) I used to carry these type of stroller on my website and I can still order one for you if you'd like otherwise petedge has thier own version of this too:
http://www.petedge.com/Guardian-Gear...lers-ZA445.pro
If you look at the detailed pics you will see how it works as a carseat.
If your babies are good with car rides and you dont want to keep them in an enclosed-like carrier I would recommend the My Buddy Lookout from Snoozer, it comes with 2 harness straps.