Magical inheritance.
Vida and Layla sat together in a large bare room, wearing plain sweat pants and tank-tops. It was the eve of their tenth birthday, the day they would come into their inheritance. Kenny and Martha had prepared for the high chance that it would be violent, hence why the girls were in the bare room.
Kenny, Martha, and the Potter siblings waited outside of the room until the transformations were complete.
At the stroke of twelve the twins became ten and the inheritance began. Layla doubled over, and Vida curled in on herself after falling over and clutched her head; both in agony. Layla let out a silent scream as from her back a tearing sound was heard before a pair of pure white angel wings tore violently from her back. Vida let out a glass-shattering scream as from beneath where her fingers were on her head red furry fox ears replaced her normal ears, the fingers themselves grew claws in place of her nails, and from the base of her spine a bushy, red fox tail with a white tip tore through her pants.
After the transformations stopped the sisters clung to each other as their weakened bodies shook. Vida's head was resting on her sister's chest as Layla stroked her hair and new ears.
*Vida, Layla, are you girls alright.* Aria asked once she was sure the event was over.
But they didn't reply, their minds trapped in a fog and their bodies acting on instinct. After a while the sisters finally fell asleep and the door to the room was opened, the sisters were carried up to their room and laid on their bed.
"Will they be alright?" Matilda asked.
"They'll be sore in the morning and might revert to instincts when they wake up but they should be alright." Martha answered.
"I doubt their new appendages can be hidden by glamour." Harry said.
"We'll work it out with the girls in the morning." Kenny said.
They left the sisters' room and went to their own rooms until morning came.
Short, but tells what's needed.