Smith, Hammer, Sandstad....

I am researching this for someone else... Her ancestor is Charles Iver Smith. He claims to have arrived on the Bothnia 5 May 1892. (Bothnia arrived on the 29 April in 1892 but 5 May in 1890) We know he changed his name to Smith. On his memorial service it says his parents as Mr & Mrs John Hammer of Trondjhem. He has siblings John Hammer of Grand Rapids, Wisconsin, Johan Hammer of Trondjhem and a sister Mrs Sam Benson of Blackduck, Minnesota. I found John I. Hammer consistently from 1900 on in Grand Rapids. Married to Alice and two children Ida and John/Jack. I also found him in the Norwegian Digital Archives having traveled on the Oslo in 1912 and his name there is John Iver Hammer. His birth is about 1860 and he migrated about 1880 I found Samuel Benson and his wife Christine in Blackduck consistently from 1900 as well. Christine was born about 1875. I've been searching the Baptisms at familysearch.org also been searching the 1875 Norway Census at the digital archives and am not getting anywhere. I've tried the Hammer surname, but also have been trying Johnson et al as well since the patrynomic naming pattern was still in use at that time. There is also a marriage certificate which it is believed to be Charles and his wife Olgas. Names are C. I. Sandstad and Olga Petersen. Marriage is 23 Dec 1902 Spokane WA. I am still not convinced this is thier marriage as thier son Harry was born in 24 Mar 1901. But I have compared signatures on the marriage cert and his WWI Draft card and there are definate similarities in the signatures. Charles (who I assume was born Carl/Karl) served in the Spanish American War, 3 yrs at Ft Snelling in Minnesota. (Did find a Carl Hammer who lived in SD, served in the Minnesota Volunteers) and the Cuban Campaign. before settling in Spokane in 1900. I haven't found him on the 1900 Census yet though. He is said to have fathered a girl child prior to his marriage and settling in Spokane. Child is referred to in his will but not named. This is my first time researching Norwegian ancestors so I am not sure where to go to from here.