Board Thread:Show-Related Questions and Answers/@comment-25974054-20150105192131/@comment-25926288-20151019195539

Ingrid could have left anytime in season 2 or 3 before the midseason finale.

Ingrid could leave and forget her time in SB and still go back because Ingrid would be back to where she started and she has the Apprentice's scroll that tells her the prophecy.

Anyway, it has been established that if you don't come by the curse then you get to stay if you leave the field of view.

What? They said the opposite, but claearly Ursula and Cruella didn't go back, so we know that what Regina said was wrong and that's that. Plus, Lily would have been dragged back and Mal wouldn't have to go worry about her.