Dear Ms. Gabusi,
Thank you for posting your request on History Hub!
We searched the National Catalog and located Population Schedules for the 1910 Census; Population Schedules for the 1920 Census; and Population Schedules for the 1930 Census in the Records of the Bureau of the Census (Record Group 29) and found Alexander Demjanovich listed in the 1910 and 1920 censuses; and Edward Demjanovich in the 1930 census. Some records are digitized and available in the Catalog but not those for New Jersey. For access to and/or copies, please contact the National Archives at Washington - Textual Reference (RDT1) via email at firstname.lastname@example.org. We were unable to identify a family connection with Alexander and Edward in these census records.
We also searched Ancestry and located Alexander living with his wife Johanna & 5 kids on the 1910 census; Alexander as a widower still living with his 5 children; and Edward on the 1930 census at age 1 living with his parents and sister. We also located a 1925 Death Record for Alexander; and his Grave site. There may be a fee for using Ancestry to access digitized records. However, you may view these records online at one of NARA's facilities for free via a NARA PC. For the nearest NARA location, please consult our web page at https://www.archives.gov/locations/.
You may wish to review the New Jersey State Archives website for genealogical resources that may assist with your research.
We hope this is helpful. Best of luck with your family research!