There has been a big petition to make Leia Organa a Disney princess. But we can't do that. 

My favorite character is Leia. So it's not that I don't like her. She just can't be a Disney princess.
Disney Princess isn't simply being a princess in a Disney movie. It's a "title", a franchise. It's an error to call Kida, Nala, Esmeralda or Leia (to give a few examples) Disney Princesses. There are several restrictions to being a Disney princess. 1st, you need to be a human. Leia's got that covered. 2nd, you need to have appeared for the first time in a film that isn't a sequel. Although some might debate about this point for Leia, let's say she's got it covered. She needs to have popularity amongst Disney fans (aka box office success), and Leia's got that covered.
The thing is, we could argue for hours. But the last point is the key here. You need to be animated. Sure, there's an animated version of Leia (SWR) but the reason is for Disney Parks. You can have any woman walking around as Belle, Snow White or Cinderella because their "official" face is animated and therefore can be interpreted as a human face in any way anybody wants. So even if there is an animated version of Leia, that's not the issue. The issue is that there is an actress baring her face. It's the same reason for which Giselle isn't a Disney princess. They can't just have Amy Adams walking around Disney parks and any other woman wouldn't work since the face isn't the same. Same goes for Carrie Fisher, even if we were still in the 80s where she had her "original" Leia appearance.
Not only that, but Disney also decided not to have more than one Disney Princess per franchise/series. That's why the Frozen sisters aren't in. Sure, only Anna is the princess in the group, but Elsa was also a princess once before she was queen and besides a royal title hasn't stopped Disney from naming a Disney Princess before so it doesn't matter that much (like Mulan, for example). The thing is, if both Anna and Elsa are eligible for the title, which one do they take? Elsa seems to be more popular but it would be a little weird to keep Anna away from the whole Disney Princess experience, wouldn't it? Especially if her sister, a queen, is inside of it. Same could go for Leia. If they put her in the franchise (which wont happen), it could seem off or unfair that Padmé (who was princess of Theed then Queen of Naboo) or even Rey weren't included too.
So I could go on for a long time, but these are the main points. So please understand that making Leia a Disney Princess makes no sense and won't happen, and stop annoying Disney with the idea.

And pelase, please, stop using Carrie Fisher's horrible passing to throw a petition at Disney. It won't do you any good. 

Disney, please do not get influenced by what thoughtless fans say and sign in big numbers. Real Disney fans know that this isn't a good idea.