I would love to get a line on Margaret Burns, especially since her nephew, John McElvaney, named a son Robert Burns McElvaney. The Scottish poet Robert Burns, born 1759, had a brother who moved to Ireland. I suspect Burns was her married name, because of the 1860 census (below), but haven't found her with a husband.
1880 Census of 2nd District, Howard Co, MD, ED 102, p 355D - 1 June 1880
John McElvaney, age 47, b IRE father b IRE mother b IRE, Works on R.R.
Rebecca McElvaney, age 47, Wife, b NY father b IRE mother b ??
James McElvaney, age 21, Son, b MD father b IRE mother b NY, Works in Cotton Mill
Robert McElvaney, age 16, Son, b MD father b IRE mother b NY, Works in Cotton Mill [found elsewhere to be Robert Burns McElvaney]
Rebecca McElvaney, age 11, Dau, b MD father b IRE mother b NY
Annie McElvaney, age 8, Dau, b MD father b IRE mother b NY
Margaret Burns, age 87, Aunt, b IRE father b IRE mother b IRE
Given the 40 years' difference between the ages of John and Rebecca and the age of Aunt Margaret Burns, it is most likely Margaret was John's grand-aunt. Notably, perhaps, Margaret Burns was about eight years older than John's mother, and John's mother and father named a daughter Margaret.
With the age discrepancy, I'm not certain this is the same Margaret Burns ...
1860 Census of Little Gunpowder, 13th District, Baltimore, MD, p 280(B) - 9 August
Margaret Burns, age 63, b IRE, No Occupation
Margaret was living alone.On p. 269, also in Little Gunpowder, are Peter and Mary Burns, 33 and 30 respectively, both born in Ireland, with children Michael age 7, John age 4, and Thomas age 2, all born in Maryland.