Looking for Kristine Fleskhus in Trondheim area

In finding my ancestors, I have lost a young girl-I have no idea where she went at three years of age. My grandmother's sister, Kari Nilsdatter (born in Selbu Norway on March 16, 1859) married Andreas Andersen Fleskhus (born in Verdal, Nord-Trondelag in 1845) in 1885 and they lived in Trondheim. Kristine was born in 1885 also, not sure which month. Kari, her mother, died in 1888 when Kristine was only 3 years old. I have no idea where Kristine ended up living and with who. In the 1900 census Andreas is living with his new wife, Gurine and daughter, Helene (born in 1889) in Trondheim with no mention of little Kristine who would have been just five years old then. I don't think she is with anyone in Grandmother's family as Grandmother and her sisters, Ane, Marit and Sigrid came to America (with no mention of a Kristine with them). Jonas died quite young and Peder was on the Sæter farm in 1900 with his family with no mention of Kristine. I haven't followed Andreas' family yet-not sure if I can as I haven't tried-but that will be the next thing as maybe someone in his family took her in? I don't know the customs back then but I would have thought the father would have taken her--but--MAYBE he isn't the father? I have no reason to think he isn't but who knows? Does anyone have any ideas how to find this little girl? Any help or information would be appreciated. Deb