Enchant her tits

"Here's a trick I haven't done in a while," you say.

You give Lydia a little swat on the ass, placing a simple enchantment on her. You then produce a small, hand-held dial, which you show to the young elves.

"You see this dial?" you say to them. "If you want to see her with small breasts, you turn it to the left. If you would rather make her breasts grow, turn it to the right. See?"

"Don't you dare--"

The princess tries to grab the dial, but you crank it up to the right and send her right off balance. A pair of oversized boobs spill out all around her bra cups. You then turn it all the way left, and the garment sags off of a completely flat chest.

"I just saw her nipples!" says one of the younger elves.

"You sure did!" you say. "And that's just the nip of the iceberg! Here, give it a try."

"I bet I can break her bra off!"

"Let's make her really flat! It'll be funny!"

Lydia gives you a look and takes off running as fast as she can.