This story is a side prequel to Little Jewels. (Read that one first.)

http://www.fimfiction.net/story/155509/little-jewels

When Twilight is given a new spell to practice, she asks her friends to bring some aged stuff for target practice. But when the spell gets out of hand, it turns all of the Mane 6 into foals. They still retain the ability to talk though. What else comes as a surprise is that their new Mamas are Celestia and Luna. I can see things looking up from here.

WARNING!!! THIS IS A FAIR WARNING THAT YOU SHOULD LISTEN TO THIS TIME!!!!! This fic contains Age Regression, Diapers, Breastfeeding, and a slew of other foalish things. Please consult a doctor before consuming this fanfic. Do not read if you cannot stand cuteness and baby ponies. Don't try to imitate the events of this fic at home.

I MEAN IT THIS TIME!!!

Princess Luna has been through a tough life. A thousand years ago she could not control her jealousy, envy and rage and became the infamous Nightmare Moon. Then, she spent a thousand years on the moon, only to return, still as Nightmare Moon.

However, despite everything she has been through, her return to Equestria was warmly celebrated. Princess Luna is a pony that everypony loves, and she is completely forgiven for everything that's happened.

So, when Princess Luna is suddenly and unexpectedly killed, the entire nation of Equestria is thrown into grief and despair. Ponies everywhere find themselves unable to deal with the tragedy.

But the worst hit is Princess Celestia herself...