I have a 19 month old and a Clek Foonf, which I've heard they can use practically forever......but what would come after the Clek for her and around what age? (I know that depends on height and weight).

Generally, she's around 80% for height and 45% for weight.

We're going to have another LO and we just have 1 car--I want to buy as few car seat products as possible, but I also want the possibility of 2 car seats and an adult (the adult can be a little squished) or 3 car seats in the future.

I'm already thinking about convertible seats for #2. We also travel a fair amount, so the super heavy seats like the Clek aren't the best for flights. I like the idea of the Combi Cocorro, but I heard LOs grow out of them by 3-3.5ish. My older LO would be 5-5.5 at that age.

Could she move from the Foonf to something else, passing the Foonf down to LO #2 at that point?

Or should I just go for another super heavy seat like another Foonf or a Radian?