My oldest brother I did him torture
I tortured him till he had to fly
All on account of the girl he married
And still in anger I did rage
To the place where his child was buried
I went by night and dug up the grave

This rather lurid verse from the song is supported by local history. The Riley family had a Catholic plot. When the Gull Decoy died he was buried in his own plot away from his family's. In this song and in one about Riley's son he is described as a heretic and restricted from communion and the rites of the church. Sandy Ives doesn't mention any info beyond the rumoured stories of his informants [there is a rare book of a descendent who writes about the Riley family that I need to get] so the reason for the Decoy's ex-communication is not stated. I began checking old land maps and census and found Riley and many of the people and local references in the songs. The 1881 census says Riley was 76 years old. His Religious identification is . . . "Infidell"!
Here is a Government historic monument page for the Riley family plot that provides more of the shocking details of the Gull Decoy's actions against a brother who married a Protestant

https://www.historicplaces.ca/en/rep-reg/place-lieu.aspx?id=13052