In your scenario, I would list her as child of her mother’s marriage, as her legal father was the man she thought of as such as she grew up; I would add her biological father with her mother as a second set of parents with an explanatory note.
This is why I started this thread, as her bio father was never a spouse to her mother, nor even a partner; as my aforementioned distant cousin called her biological father, he was nothing more than the sperm donor. I feel that as genealogists, we could come up with a different term than simply lumping couple who who had children but did not marry not even live together as “spouses”.
I have a number of half-siblings (my mother married three times and had children by each husband), and I count them as children of each respective couple. The exception is my sister, who was adopted and raised by my father, and never met her biological father.
I list her with two sets of parents (as RMG allows), our mother and her biological father, and our mother and the dad who raised her (and is her legal father).
Legally, since her adoption was completed before my birth, she and I are full siblings, according to the law.
Work at it long enough, and you’ll find all sorts of unusual relationships. On the topic of convoluted relationships, one set of great-great grandparents in my line married after each had been previously married and had families with said previous spouses. My great-great grandfather had daughters who were almost as old as my great-great grandmother’s youngest brothers; two of his daughters married two of her brothers. The two men were simultaneously my great-great grandfather’s sons-in-law AND his brothers-in-law, while their wives were my great-great grandmother’s step-daughters AND sisters-in-law. I don’t have to worry about any labels here, but it sometimes hurts my head to explain it.
I also have seventh-great grandparents who were step-siblings to each other; his father and her mother remarried when he was 19 and she 14, and they married when he was 24 and she 19. Again, no labels needed, just a note of the unusual nature of the events.