Re: Did you need a 40 lb limit to RF until age 4?
I didn't make it to age 4 with DD1. She hit 36lbs just before she turned 3, which was just past the limit of her seat so she turned FF. I weighed her about 4 months after she turned 3 and she was 40lbs. She's only just now pushing the 45lbs mark at 2 months past her 5th birthday.
DD2 is trending much smaller than her sister was, so 40lbs should get her easily to 4.