Americanization of Norwegian names

Hi, I understand that many Norwegians that emigrated to the states would adapt their names to better fit with the English language once in the US. My question: how might names such as Henrik Christiansen and Sivert Christiansen be "americanized"? Background: My great-great-grandmother had at least three siblings that emigrated in the 1880s. We have a case full of photographs sent to her from the states, but no names are written on them. Most are taken in studios in or around Chicago. I have located one sister in Illinois and assume her brothers Henrik and Sivert are on the other photographs, but I cannot find them on the censuces or in the death notices. Maybe I am searching the databases with the incorrect names? Maybe I should try some "americanized" names? Thanks for any suggestions!