Looking for Steffen Halvorsen and family

Hello! I am looking for help on finding great-great-great grandparents, Steffen Halvorsen and Johanna(Ericksen or Eriksen)/Halvorsen..There children are as follows...Gunhild Mary or Marie Steffensen, Thea Steffensen, Sophia Steffensen, Nettie Steffensen, Eliza Steffensen, Carl Steffensen/Halvorsen, Hans Steffensen/Halvorsen, Andrew Steffensen/Halvorsen. Hans came to the U.S. between 1880 and 1881. He worked appoximately 3 yrs in Manistique, Michigan to save and send the money to Steffen and Johanna so they could come to Manistique, Michigan with the rest of the children. I am told Steffen, Johanna and the children arrived in the U.S. in 1883..I have tracked them in the census records in Manistique, Michigan but according to those census records from 1900 to 1930, the dates of their arrival to the U.S. say 1881, 1882,1883,1884, and 1885! I need some confimation as to the right date they came to the U.S. and what boat/ship/vessel, etc. they traveled on. Also, if anyone could help me find them in the census records in Norway, the help would be greatly appreciated. I do know Steffen was born in 1835 and Johanna Ericksen or Eriksen was born in 1836. Andrew Steffensen/Halvorsen, my great-great grandfater was born in 1870 if that is at all helpful. Thanks so much! Scarlet Krempetz