Yes, there are some out there. You can try searching on fanfiction websites. Some might focus on her relationship with her mother, or perhaps create fictional adventures for her.
If Tim Miller is a relatively unknown individual in the public eye, then there might not be a widely known story about his daughter. Maybe he is just an ordinary person, and his family stories are private and known only to those close to him.
There might be some fanfics out there that take inappropriate directions with characters like Sienna. But it's not in the spirit of the RWBY series which promotes strong, empowered characters. We should encourage fanfic writers to uphold the values of the original work and avoid creating such distasteful content.
For the most part, there isn't. The story typically refers to her as the miller's daughter. This naming convention serves the purpose of the story well. It quickly establishes her background and her relationship to the other characters, like her father the miller and the king. The story is more about the strange encounter with Rumpelstiltskin and the moral lessons it imparts rather than giving the girl a more unique name. So, no, there's not really another name for her in the main versions of the story.
In Abby Lee Miller daughter fanfic, one can anticipate different perspectives. For instance, some fanfics may be set in the world of dance competitions, similar to what Abby Lee Miller is known for, but from the daughter's point of view. It could explore her feelings of pressure or pride in being part of that world. Other fanfics might take a more emotional route, delving into how the family dynamics, especially with a mother like Abby Lee Miller, affect the daughter's mental health and self - identity. And then there are those that might be more fictionalized, creating a completely different world for the daughter to exist in, with elements of magic or adventure, while still having her connection to Abby Lee Miller as a base for the story.
There are so many possible scenarios for Tim Miller and his daughter. Maybe she overcame some difficulties with the support of her father, or maybe she is following in his footsteps in a particular area. But until we know more about this Tim Miller, we can't tell the story.
Magic exploration is also a prevalent theme. Since it's a fairy tail related fanfiction, Sienna usually gets involved in exploring different types of magic, whether it's a new form of magic she discovers or trying to understand the mysteries behind existing magic. Adventure is yet another common theme. Sienna embarks on various quests and travels to different and often dangerous places in these stories.
I'm not very familiar with this specific novel. It could be a story about Alpha Aiden and Sienna, perhaps in a fantasy or paranormal setting where Alpha might refer to a werewolf pack leader or some sort of dominant character. Without reading it, it's hard to say exactly what it's about.