Hey, just did a little further research and I think I found the answer, but it is a puzzle anyway. It looks like Springfield is the Anglo name for Magheragillerneeve, which is in Drumcliff civil parish. The puzzling part is that it is so far away from Ballidrihid. That is the townland where John and Margaret were living when they had Bridget in 1869, Margaret in 1873 and Elizabeth in 1876, even though father's homeplace was in Springfield. I guess that means he was likely not the eldest brother because Michael Johnston was having babies about the same time frame in Springfield.