CARSEAT question!

Cici • Mama and Etsy shop owner! My etsy shop is SerenadeBaby
 Having issues with my phone so I can't call chicco right now but does anyone know if the baby insert from the chicco nextfit can be used as a replacement insert with the chicco keyfit?? A friend of mine was induced early and if she needed it, I would really like to let her have the chicco keyfit. I can't for the life of me find the original bottom insert though! They do seem identical.