This is Saiba Ratzu. I changed her last name to that of Siberia's since Neutraninjians are just an "Angel" class of Starmaninjians. I wanted to redraw her to appear as she typically appears and update her look to reflect that. She is Siberia's daughter, but given she was born after Kao was (re)born, there is no father. She still ultimately refers to Kao has her grandfather, but only after the story is complete to respect her mother's wish to keep his role a secret.
1. According to the Starmaninjians, Saiba is Fang's daughter, but since Fang is a disguised version of Siberia, just as Kia is the disguise of Kiara, the secret is safe.
2. Saiba is basically Siberia but with blue hair and nails instead of pink. She does have transparent wings though, but those are aesthetic. She merely claims she's from Skylazone and has those wings cause she's an angel, allowing her to fly without question. However that assumes she appears in public very often.
3. Siberia technically gave birth to Saiba at a really young age, making her the youngest mother of all the Starmaninjians by far (at the age of around 8, and second place would be Botani who was 13 when he had Tsunami), but she had to have someone other than Kiara be her eyes and ears since she's usually busy managing the world and Kiara was pretending to be Kia to keep an eye on their revived father. Though keep in mind, Stars can reproduce at as young as 5 as that's when they reach adulthood. Amusingly, Saiba and Siberia look almost identical as a result.
4. This is actually just a note, but Siberia, Saiba, and Kao all have the same hairstyle cause Siberia genetically takes after Kao except for her fur color. Likewise Kiara takes after Sylvia and hence has longer hair.