Where could Cora have hidden her heart?

I have to believe only Cora and Regina know who's 'hearts' are who's in that vault.

Even Regina is at a disadvantage here based on what we saw in "The Doctor" episode. When she was showing Victor and Jefferson the vault and she had no idea then as to the identies of the hearts there.

Cora is the originator of this vault...scary to think she actually might have Regina's heart there as well. Wouldnt be surprised if she had her heart there, though...

I assumed it was safely tucked away in her vault somewhere.

Any ideas??

An interesting one I came across was that she put Regina's heart somewhere and hid her heart in Regina. Not exactly sure how that would work. but it was interesting nonetheless.

Another idea was that it was somewhere Wonderland and that's how Alice will be introduced. Not sure about this one but it does pique my imagination.

Anybody have anything else?