How do you know they were processed through Ellis Island?

How do you know their years of arrival in the US?

Can we assume they married?

I find no one by these names in Nye County Nevada. Did they go by different names?

The only thing I find is 1920 census record
Name: Gass Hikovich
[Gass Nikovich]
Home in 1920: Tonopah, Nye, Nevada
Age: 41 years
Estimated Birth Year: abt 1879
Birthplace: Serbia
Relation to Head of House: Head
Father's Birth Place: Serbia
Mother's Birth Place: Serbia
Marital Status: Single
Race: White
Sex: Male
Home owned: Rent
Year of Immigration: 1903

Or in 1920 census for Artesia, Lyon, Nevada

Name Age
Rado Nickovich 50
Anna Nickovich 46
Eli Nickovich 5
Rado Nickovich 4 5/12
Thomas Markovich 42

Do any of these match?

I would like to help you find both of them, but the info you gave is scant.

What are their birthyears?

Did they marry?

Did they remain in Nevada in Nye County? Or did thy move to another place?

Robert