Invisible Sister, on Disney Channel
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This first aired in 2015, but I didn't see it until 2022. Mostly I thought it was kind of "meh", but it had some elements I kind of liked, I guess.

It stars Rowan Blanchard (whom I know from Girl Meets World) as Cleo Eastman, a somewhat sarcastic, nerdy girl who feels overshadowed by her more popular older sister, Molly. Cleo only seems to have one friend, a boy named George, who, like Cleo, is good at science. Their science teacher, Mr. Perkins (Alex Désert), assigns Cleo a project which... goes awry. Without getting into too many details, I'll just say that Cleo accidentally turns a moth invisible, and Molly later swallows that moth and turns invisible, herself. So they spend the next day (Halloween) trying to figure out how to turn Molly visible again, while Cleo has to spend the day pretending to be Molly. Normally, you might think it would make more sense for Molly to stay home and have Cleo tell everyone she's sick, but that would be a problem, because Molly has to play a lacrosse game later, and won't be allowed to do so if she misses any classes. So, Cleo dons the costume Molly was supposed to wear for Halloween (Dorothy from "The Wizard of Oz") and a mask, which personally I don't think should have fooled anyone, but it did. Perhaps even more unrealistic is that Cleo also had to play lacrosse in Molly's place, and actually did a good job of it (with Molly's help). Anyway, George helps Cleo try to find a cure for Molly, and they also get some help from the boy Cleo has a crush on, Carter, who turns out to be a science whiz, himself. Another major character is Molly's best friend, Nikki, on whom George has a crush. And there's Molly's boyfriend, Coug. In the course of the movie, Cleo and Molly gain a better understanding of each other that ultimately brings them closer together as sisters.

I don't know what else to tell you.