She needs to start with her name and birthdate and work backwards. Information needs to be gleaned here in the USA before jumping the pond to Norway with hearsay information. Tonsager is Tønsager in Norway. I have the Eidsvold books, but need more information to find anything. Where did Marie go? To America? When? How do you know this? Name of her husband and where married? Children born to the couple? Who is related to you? Where did they live in America? Do you have copies of obituaries and death certificates?