Board Thread:Spoilers!/@comment-27060727-20171018191424/@comment-25926288-20171021115204

I'm thinking that this mystery girl is Eloise Gardener/Missing Girl and Hook's daughter.

After all, Hook-W's story splits from Hook when Regina doesn't cast the curse.

Let's say Hook and Hook-W were 28. Hook-W is 28 + 28 =56ish.

So, his daughter is probably in her 20s, which fits this mystery girl.

Thus, Rapunzel meets Hook-W in 7x07 and it's either his daughter's mom, or Tremaine.