Anna is 6 years old and 45 lbs; Catherine will be 5 in April, 42" and 34 lbs. Anna is in a Britax Marathon. Catherine is in a Graco something or other. Anna's Marathon will be expiring soon, and she has about outgrown it anyway. Catherine has another 7 or 8 months before hers expires. So I have to decide what to do.
My husband thinks we should just put Anna in a booster, and I guess I would be okay with that. But I'm not sure that it's the best idea. But then, while I know harnessed seats are safer than boosters, I'm not sure how MUCH safer they are. If they are 50% safer, then it's definitely worth getting a new harnessed seat. If it's 5% safer, I'm not sure. It's one thing to keep a 6 or 7 year old in a harnessed seat; it feels like another thing altogether to purchase a harnessed seat for a 6 year old.
I'm less okay with moving Catherine into a booster. Even in seven months, she'll still be 5.5, but likely still under 40 lbs.
So, I don't know what to do. I've looked at the Graco Nautilus, the Britax Frontier, and the Regent. (I know they're discontinued, but I think I could find one, and for a similar price to the Nautilus.)
So it seems like I have several options:
1) Put Anna in a high backed booster now, and leave Catherine in her seat. Move Catherine into a booster when her seat expires.
2) Put Anna in a high backed booster now, but purchase a new seat for Catherine in seven months.
3) Buy a new seat for Anna, and when Catherine's seat expires, move Anna into a booster and Catherine into the new seat.
I'm leaning towards either 1 or 3. If there is not a significant safety margin, #1 seems reasonable. If it makes a definitely difference, then #3 seems like the best solution. But then, which seat?
So, I'm putting myself in your hands. Tell me what to do!
There is no data showing that boosters are more or less safe than harnessed seats for kids who are atleast 4yo and 40lbs who can sit properly in the seatbelt. If your oldest can sit fine in a belt, then I would definitely do a high back booster for her. Your 5.5 yo may be ok, but she's still pretty small. I would probably look into a nautilus or frontier for her when her seat expires. But I'd wait and see how heavy and mature she is (maybe start booster training her on occassion) when her seat expires.