Amundson and Pettersen links?

My grandfather Edvard B. Pettersen came from Trondheim, Norway to Georgeville, Minnesota in 1903. His fare was paid for by his cousin Hans Amundson who was living in Minnesota at the time. I have been trying to find a link between these two people but not having much success? I was hoping there might be someone who could put these two families together? My grandfather changed his name from Pettersen to Eide, the family does not know why? Thanks for any help you can offer.