We already have Navigo Decouverte cards from a previous trip. Can we load a carnet of single use tickets to that card, or would we need to buy a Navigo Easy? Thank you!
Navigo Decouverte can't hold carnets of single-use Paris Metro tickets currently so you'll need to buy a Navigo Easy card for carnets.
Navigo Easy now provides a 2€ discount to the cost of a 10-ticket carnet so the price of the card is effectively free.