With modern society some things are getting harder to track. There are more marriages and children out of wedlock. People are easily traveling longer distances. I recall one 17-day trip to arrive way out west. The men traveled all the way from Philadelphia to Pittsburgh.
Letters requesting information often bring no response.
Others bring promises and no data. If you have access to people from an older generation a tape recorder can work wonders. Do not accept or discard anything. Even official sources and adamant relatives are often wrong. When you get varied facts for the same individual or family, record them all.