So, after 2 accidents I think I need to replace my seats. I had a Graco Affix, a Parkway backless and a Frontier in my van. My DD usually rides in the Affix since most of the time it is to school for drop off. She is 45 inches tall, 42 pounds and 5.5 years old. My DS is usually in the Parkway backless. He is about 55 inches tall, 68 pounds and 9.5 years old. What would you recommend for them? They ride in a Nautilus and an Affix backless in our other car. I really would prefer latchable boosters because they are easier for me.