Just as with the modern practice of social networking in genealogy is the practice of networking ancestral families and their associates.
Many times a particular problem of identity can be solved by analyzing an ancestor’s associates in detail. In-depth research of this sort requires the serious genealogist to document the ancestor’s neighbors, business associates, and in-laws. The latter may be the most important, and potentially the easiest to document as the families are related. With common names, and people of the same name in the area, familial relationships are also important. In-laws and relatives are the people to focus on when examining wills and land transfers. In business dealings such as personal property item transfers, such as when an estate is distributed, a neighbor probably bought an item.
When it comes to neighbors and business associates, it may be necessary to document an entire neighborhood, or even a village. I recall one article in Forensic Genealogy (ISBN-10: 0976716003 ISBN-13: 978-0976716006) which detailed one woman’s efforts to document her earliest known ancestors in a French village. It was a fascinating account of documenting the lives of people who lived through a difficult migration, famine, and pestilence.
Other groups of people, such as church members, are also sometimes important, too, beyond just those whom the ancestor lived and worked with. A minister, for instance sometimes performed marriages for cousins and other relatives in other communities which shared a minister. In some instances, it may be possible to document the minister’s relationship to the family through church records. If the minister’s records have been preserved in a seminary or society collection one may be able to find the records of other members of an extended family. A real goldmine of information would be to find lists of best men and women, and bridesmaids for each marriage in a churches records.