iFly Connect detects SD cards that are configured with iFly software and data. That's intended to help ensure the potentially-ginormous amounts of iFly data go to the right place and don't waste your time and cause confusion by inadvertently getting put onto a random USB thumbdrive or getting mixed up with pictures of the grandkids on your camera's SD card.
To set up a new card, take an existing iFly SD card and copy its contents over to the new cards. (If you don't have a way to access two SD cards simultaneously, or if you're going to set up multiple new cards, it may be best to copy the iFly SD card contents to your PC's hard drive, then from the hard drive to the new SD card(s).)
Make sure you copy the files (so the original SD card is unchanged)--don't move them (where the files are deleted from the original SD card during the process).
Once the new SD cards have the iFly data on them, iFly Connect will recognize them and allow you to update them.