Re: Looking for info on Family Name Folis or Tolis in Eastern Poland #poland
Have you located their U.S. naturalization documents or passenger manifest?
A good site to begin your search is: www.familysearch.org
Have you searched the databases at JewishGen for records from Poland and other countries? https://www.jewishgen.org/databases/
They may have chosen at some point to change their surname, but their name was not "changed at Ellis Island." Names were sometimes spelled incorrectly when the manifests were written up in Europe.
As to two family members spelling the surname differently, I have seen that previously. It is not unheard of.