Mathias Andersen Olstad Wisconsin Minnesota

Hello! There have been ruomers for over 100 years that my great grandfather Mathias Andersen Olstad had a second family in America. He is born in ringsaker, Hedmark in 1869 (or 72).. He married here in Norway with Anna and got seven children with his norwegian wife, but he spend around 17 years in America, and took several trips there before and after he was married to Anna. Before he went on his last trip he said he had to go there to "fix things". He was gone for 2-3 years.... He worked at Nils Persons (Or Pedersen?) brothers farm in Wisconsin, Minnesota. Nils Person was married to Mathias`s mother, and his brother lived in America. (Dont know his name!)The Persons came from Sweden. I found a record on Mathias in a passenger list from 1905. He arrived there on the majestic ship... I think that was his second trip there after he got married with Anna. I can`t find out anything more about him and his trips!!! If he really did have a second family there, my grandmother has siblings in America! (Probably they are not still alive, but my grandmother who is a healthy woman born in 1925 would probably have nieces and nephews there....) I really appreciate all help i can get, cause im not an expert in searching for ancestors....! Thank you so much. [:)] All the best Siw-Hege Bredesen, Norway