Parents have one car seat which they bought for our eldest child a few years ago. They asked us which one and we told them and they bought it. We now have 2 children. They've been borrowing one of our car seats whenever they take them both but now they've said they've bought their own second seat. Only thing is, I don't like the seat they've bought. It's a re-brand of a cheap generic Chinese seat and it's not properly crash tested to the same standard as our other seats. I don't want my kids in it. Am I ok in telling them that? Or seeing as it's their car and they paid should I just suck it up. For information, because I know it'll be asked, they have the children because they want to, not as regular childcare, so we don't need them to have them.