Thanks, ShaunJ. Yes, I have come across a similar article.
I looked at the 1920 census for Gordon Guiberson, and his mother Ethel L Guiberson was aged 43 and born in Nevada, so she was born about 1876/1877. Ethel Lavinia Heanan married Samuel Guiberson in 1906.
In the 1900 census Ethel's mother Mary was described as a widow, aged 47, so born 1852/3. The 1900 also says that Ethel's father was born in Scotland.
In 1880 Charles O Heenan, labourer, aged 32, born Scotland, wife Mary, son A M Heenan, 6 and daughter Ethel Heenan, 4, were in Austin City, Lander County, Nevada.
So he must have been born about 1847/1848. There are no Charles Heanans in the available Scottish records, not even using 'name variants' in the search, and no Charles Heenan (or variants) in the Scottish census in 1861.
So if Charles Dominic and John Rupert were born in the 1890s, they cannot have been legitimate half-siblings of Ethel Lavinia Heanan or Guiberson, because her mother was still living in 1900.
Did Charles Oris Heanan abandon his wife Mary, cross the Atlantic and bigamously marry Alice Sarah Wyllie? Or was the Charles Oris Heanan who married Alice Sarah Wyllie a completely different person with the same name?