The gallery initially labelled the piece “Cathy’s Dad”, believing it to depict McGuiness’ father-in-law.
However, the artist’s daughter Corinne Aspel said she “knew right away” it was not him when she saw the drawing.
“It wasn’t my grandad, there are clear differences – particularly in the shape of his nose,” she said.
The name has been changed to “Portrait of an Unknown Man” – for now.
The exhibition, Tom McGuiness: Out of the Darkness, will run throughout the rest of this year and feature oil paintings, sketches, lithographs and personal family portraits by the artist.
Born in 1926, McGuinness was one of the Bevin Boys conscripted to work in coal mines during World War Two and died aged 80 in 2006.
Sutherland said: “This exhibition celebrates a man whose work captures the emotional truth of mining life, as Tom interpreted what it felt like to be a miner.
“His art remains a powerful reminder of the resilience and identity of mining communities across the North East.”