Edward's father Duncan Kirkwood married Elizabeth Stewart in Berry Street Presbyterian Church Belfast in 1871. Duncan Kirkwood's father was William, a dresser in a family, while Elizabeth Stewart's father was James Stewart, a land steward.
As well as Edward in 1874, the couple had Walter in 1872, Duncan in 1876, Agnes in 1880 and Sarah in 1884 - details in familysearch.
Correction: Duncan's father William was a dresser in a factory