Hi @jennolvera1, good to see you around.
In this regard the Ionic should behave the same as the Blaze. As long as you log into the same account on the fitbit app on both devices, the Ionic should already be in your account on the second device. One thing to remember though is to turn off Bluetooth on the secondary device so that the Ionic can sync with the device you are using. If both devices have it switched on at the same time it can cause interference and effect syncing.