searching Anne Halvorsen family

Looking for family of Anne Halvorsen. Anne's death record lists DOB of Apr 2, 1853 in Norway(unfortunately not sure where), 1885 census lists her as 28 years, which may mean a year of around 1856 or so, 1900 census lists birth of Apr. 1854. Dad is listed as Halvor Halvorson and mother, Marit on Anne's death record (informant was husband, Gulbrand (Gilbert) Sorbo). Census lists immigration year of 1865 for Anne or Anna. Her family probably settled in Iowa. Gulbrand and Anne raised their family in Worth and Winnebago counties in Iowa. I have the 1880, 1885, 1895, 1900, and 1905 census for Gulbrand and Anna in Iowa. However, I'm trying to connect Anna with the right family from Norway and who may have come over to the U.S. I have her husband, Gulbrand Sorbo family traced. They came from Valdres in Oppland in 1842 and that sure doesn't mean that was where Anna was from. Any guidance greatly appreciated. Vicky King