kitty-carroll.org

In development — at least to the extent of setting up a casting call — at the Disney Channel:

Invisible Sister will tell the hilarious story of a good-natured, bookish young girl named Cleo who accidentally makes her super popular sister Molly invisible after the science project she is working on gets out of control. Now Cleo has to figure out a way to turn her sister back to normal and Molly gets a powerful look at what life is like when no one sees you.

There had been some chatter to the effect that this project might have been based on the book My Invisible Sister by Beatrice Colin and Sara Pinto, but the plot synopsis as given sounds nothing like that book.