Thomas mulligan father and son with same name

Hi all.
my names james mulligan and my father his name was james to born 5 feb 1945 to Thomas mulligan and Helena Mulligan/McDonnell. Thomas died in 1950 from TB, and at the time his father lived in woodrouffe cottages in islandbridge I would love to get some information on my great grand parents I believe he also may have a brother and sister Gerard and Lilly

Thanking you