Snowcinder

Snowcinder is the femslash ship between Cinderella and Snow White from the Once Upon A Time and Disney fandoms.

Enchanted Forest
Cinderella first meets Snow White at Prince Thomas's ball, when Cinderella notices the prince she asks Snow if he is "charming" to which she tells Cinderella that the title of "Prince Charming" has already been given to someone else. When another one of Thomas's balls allowed the two to cross paths with each other again, Snow dances with Cinderella so she can tell her that she is happy for her.

Storybrooke
Sometime after Mary Margaret (Snow White's curse name in Storybrooke) gave birth to her son Neal, she begins to attend parenting classes that are run by her friend Ashley Boyd (Cinderella's curse name in Storybrooke).

Fanon
While the ship is commonly focused on OUaT's version of the two, there are fans who use ship and its commonly used title with Disney's versions of them within the Disney Princess part of the Disney fandom, since the ABC television series has its own versions of the Disney characters and has a few traits from its series; and it being the live-action show that helped to trigger the ship or had helped to make it popular in both fandoms. The Cinderella that Once Snow White is shipped with is the first one, Ashley Boyd, as she is more closely like Disney's Cinderella; while the second Once Cinderella (Jacinda Vidrio) is the OUaT series own version of her and is also the mother of Mary Margaret's great-granddaughter.

Because Ralph Breaks the Interest is a canon Disney crossover that has a version of the two know each other, like their once counterparts do in the Once Upon A Time series, fans of the Disney side of the ship sometimes have Snow White and Cinderella in the modern, style clothes that the netizen versions of them wear in the film.

On AO3, the Disney side of the ship has 10 fanfics while the OUaT side of it has only 2.

Fandom
FAN FICTION
 * Snow White/Cinderella (Disney) on FanFiction.Net
 * Snow White/Cinderella (Sofia the First) on FanFiction.Net
 * Snow White/Cinderella (Kingdom Hearts) on FanFiction.Net
 * Mary/Ashley (Once Upon A Time) on FanFiction.Net
 * Snow White/Cinderella (Kingdom Hearts) on FanFiction.Net
 * Mary/Ashley (Once Upon A Time) on FanFiction.Net

Trivia

 * In the Disney film, Ralph Breaks the Internet, Snow White and Cinderella appear as online versions of themselves known as "netizens", the inhabitants of the digital made world that lies within the real-life internet. Where they are two of the fourteen Disney Princesses that are from the expo-like Disney website, Oh My Disney.
 * Both Snow White and Mulan appear in the Disney Junior series show, Sofia the First, when the Amulet of Avalor summoned them to aid Sofia.
 * Both Snow White and Cinderella appear twice in the Kingdom Hearts series, where they are featured as two of the first seven Princesses of Hearts.
 * After the light in their hearts were used to unlock Kingdom Hearts, the two, along with the four other captured Princesses of Hearts, choose to stay in Hollow Bastion so they could keep the darkness at bay until Sora sealed it with his Keyblade and the Princesses were finally able to return home to their own worlds. When they're roles were completed the pure lights in their hearts were passed onto other princesses.
 * Snow White is the first Disney Princess, while Cinderella is the second.