Yes, I understand you are trying to trace Michael's wife and child but it helps to post details already known to save others from searching for clues when trying to help you.
During World War I it was common for local newspapers to publish details of serving soldiers ('Mrs. Smyth has heard from her son Thomas serving with the 1st Bn..., etc.) and deaths of those soldiers (sometimes with a photograph) but you'd probably need to check the Mullingar papers.
