Heggen in Illinois, Iowa

I was under the impression that my great-grandfather, Torchel Gotskalksen Heggen (26 Dec 1826-21 April 1908) -- son of Gotskalk Olsen Heggen (21 Feb 1796-1876) and Anna Salmonsdatter (1795-1877) -- immigrated to America (Kendall/Grundy Counties, Illinois) in 1854 from Ølen, Hordaland . . . by himself. I have his siblings as Ingeborg (1826-?), Gotskalk (6 June 1835–13 May 1890), Ingegborg (1838-?) and Synneva (1853-?), none of whom immigrated. But I've recently learned that Torchel may have immigrated in 1855 with two brothers, Lars Heggen, and Solamon Heggen(1823-1887) married to Sigrid Olsen (1824-?); and a cousin, Ole Olsen Heggen, settling first in Lisbon, Kendall County, Illinois, then in Huxley, Story County, Iowa. Can anyone help me confirm that these individuals were related to Torchel and that they immigrated together? Tusen Takk, Don