I've found out some information, and if you can tie it in with your family tree, then that will be great. My granfather, James Dignan (b 1892, Edinburgh) was one of six children. The others were Thomas, Sarah, Robert, John, and Margaret.
His parents were James (b 1865) and Helen Lyall. G-grandfather James had Philip, Thomas, Patrick and Margaret as siblings.
Their parents were Thomas Dignan and Bridget Clark. Thomas's siblings were Patrick, Frank, and Bridget/Brigidam.
Thomas was born in Killukin, Roscommon, Ireland, circa 1840, Bridget was born in Edinburgh. It's thought that Thomas lived in Dundee before moving to Edinburgh. It's plausible that his parents Bernard (or Bernardi) and Mary (or Mairea, nee Daly) were also living in Dundee, and that they excaped the potato famine to Scotland, but it's equally possible that the parents stayed in Ireland.