Genealogy puzzle

I'm figuring out my family tree the hard way, by not using Ancestry or other for pay genealogy search companies.  I'm having great success with my mother's side of the family tree.  Riding high on the success of that, I decided to try figuring out my father's side of the tree.  I had delayed doing his side for two reasons:  1. I had the tree back to 1904 when my father's grandparents came here from Sweden, and anything further would either require using a paid service, or reading comrehension of Swedish; and 2. For some unknown reason, all my father's family emigrated here with the name of Olsson, but by the 1910 U.S. census, they all had taken the last name of Silverstrim.

Now the family story of this was that my great-grandfather, Magnus Olsson was coming to join his brother, Nils (later changed to Nels, then Nelson).  Magnus brought his wife and about six of their kids with them.  That checks out on the Ellis Island immigration forms, because Magnus clearly states that he is coming to join his brother, N. Silverstrim.  This is the first instance I've found of anyone in my family using the name Silverstrim.

So then I ask family members where Silverstrim came from.  The family members say that Nils was serving in the Swedish Navy and jumped ship when they got close to America.  Somehow he either got on board or was picked up by another ship carrying Jewish immigrants, and Nils changed his last name to Silverstein or Silverstrim to blend in with the Jewish immigrants and to hide from the authorities of the Swedish Navy who were looking for him.  This occurred in 1889.

Okay, all this is sorta plausible, initially, but where I question all this is, after he gets into the U.S., why did he continue using the false name?  Swedish officials didn't have authority to search for him  on U.S.soil.  Then, when his brother, Magnus and family come to join him in 1904, Magnus says he's coming to join his brother, and gives his name and address.  Surely if he were worried about being discovered, he wouldn't have wanted Magnus to put his information on the immgration paperwork.  Maybe since it was 15 years later the Swedish authorities weren't looking for him anymore?  So why not go back to his name of Olsson?

Then the story gets stranger.  In 1904 Magnus and family come into the U.S. with the name of Olsson, but by the 1910 U.S. Census, they have all changed their names to Silverstrim.  Why would they do that?  Family members say older family members told them they changed their names to blend in, in the U.S.  Olsson is a much simpler and more common name than Silverstrim, so that story doesn't sound plausible to me.  I know from a Swedish genealogist that the first Silverstrim in Sweden was a Polish Jew.

So now I'm trying to work my way back further, which might require a paid service, and trying to figure out this whole name change business.