From the early 1950s when Jean Paton began Orphan Voyage, and into the 1970s with the creation of ALMA, International Soundex Reunion Registry, Yesterday's Children, Concerned United Birthparents, Triadoption Library, and dozens of other local search and reunion organizations, there has been a grass roots support system in place for those seeking information and reunion with family.
In all adoption searches, it is uncommon to find both the birth mother and father at the same time. A separate search, if desired, can be done afterwards for the father. Since males seldom change their surnames, and the mother might have additional information, it is usually easier than the initial search for the birth mother. In many cases, adoptees are able to do this second search for their birth father by themselves (or they try before paying for assistance).