We want to buy three navigator easy passes at the Gare du nord on a Sunday. We then want to load them with day passes for the Wednesday and Thursday
Buy Navigo Easy passes at Gare du Nord ticket windows for Metro, RER or Transilien trains. (Passes are not sold at TGV/SNCF ticket offices.)
The ticket seller can also load the two Navigo day passes for Wednesday & Thursday for you at the same time. You can pay in euro cash or credit card. Or if you prefer, you can purchase just the Navigo Easy card itself (2 euros each) and take them to an automated ticket vending machine with a Navigo pass reader and purchase/load the day passes yourself. There will be flags on the machine screen to allow language selection (to English, etc.). Then you'll need to navigate your way through screens to find Navigo Day Passes and select the days (up to 6 days in the future) for their validity. You'll need to do each Navigo Easy pass separately in 3 different transactions.