Transfer PS4 Plus subscription to another account?

I'm surprised that you're unable to get a refund for your PS+ subscription. According to the FAQ, you're entitled to a (reduced) refund when you cancel your PS+ subscription.

You can find information on how to request a refund here: https://www.playstation.com/en-gb/get-help/help-library/playstation-plus/playstation-plus/playstation-plus-cancellation-policy-/

Alternatively if you added PS+ via a voucher, you cannot get a refund since the purchase was made outside the PS store.

In that case you can set her dad's account as master account and your daughter's account as a linked/sub.

http://manuals.playstation.net/document/gb/ps4/settings/activation.html

The linked account will have access to the master accounts PS+ free monthly games and online multiplayer, the only feature that doesn't share over is the online cloud storage for save data backup.