I already play Junes Journey. My wife want to play having her own game. We use the same iPad, can a..

Yes, if you both have separate Facebook accounts. Each game will need to be connected to its own Facebook account to backup the game. To switch, you'll need to log out of your game in the game settings, under Social tab, "edit connection" and "log out". Then you must also log out of Facebook. She will have to log into her Facebook account and start her game. This must be done every time you switch players.