Penelope Starshine

[Gift Jeraff]

It would be cool for someone to guess something this big ahead of time.

Because no one guessed that Ian would be the prisoner of Elan's father years before we even met Tarquin.

Also, basing the logic on the hair lock is such a fail because the lock runs through Mia's bloodline (if thats possible) and Ivy is Ian's sister-in-law.

Er, pretty sure she's Ian's blood sister. Geoff is his brother-in-law and Ivy's husband.
But your point still stands. Even if Penelope is Ivy, the hair lock on her daughter is not a hint because Ivy is not related to Mia.