Who burns a census

So I've had no shortage of headache over the destroyed 1890 census. I have been impressed by the skills of some of the members here to identify very hard to sort out data however and hope someone might help me with the hardest piece of my tree I've seen so far? My (adoptive) father always thought his great grand father and great uncle came over together from Norway leaving their family behind. I was able to discover from the 1900 census that this was not the case and their parents came too. They changed their name about 30 years after arriving to Bly so that made things even more difficult. The original family name in the US was Anderson and I found Christopher Anderson on the 1900 census in Lessor Township, Polk County, Minnesota. (Or I believe his name is Christopher.) He is living with his son Christ and Christ's wife Mary. Christopher's wife is listed as "Karn" and everyone thought her name was Karen. Nothing is known about her and I can't find a burial record in Minnesota. (I just found his grave last week, actually.) I can find him on the 1895 Minnesota census living with his son Andrew but his wife Karen is not listed. I don't know where she would have been since they both supposedly came in 1870 (according to the 1900 census.) They did not come immediately to Minnesota when they came in 1870. Supposedly they went to Chicago and there's a story that some records were destroyed in the Chicago fires but I have no details there. However I do show in one census that they came to Minnesota by around 1879. They arrived in Lessor Township in around 1883. Christopher Anderson appears to be born Mar 16th, 1822. Karen Anderson appears to have been born Nov 1827. Son Andrew born March 3, 1856 Son Christ (Christian?) born July 21, 1863. I have birth locations of "Kongsvinger" in family records but I also have a record that suggests they came from Akershus. Not sure if the family moved around or what happened there. I've been trying to crack this nut for the last year so any help the more talented here might provide would be greatly appreciated! Hopefully even educational. Thanks everyone! James