My SIL has given me a couple of carseats that she used for her kids- now aged 10 and 12. They are both for ages 9 mos and up. I know she hasn't been in an accident, but I'm concerned about the age of the seats. As far as I can see they look fine, and don't look all that different to the ones sold in shops now... but, would you use a ten year old carseat?