Most songs that we sing as folk songs can be found in families of songs.The Trooper and The Maid family,
The Broken Token family, Art T. has a delightful offsping in this ilk.
The Bold Sailor, Trooper, Cowboy, Tailor family.
The Lovers family.
There must be many others but this is all I can think of after a day at the New York State Fair. Songs that generally tell a story, collect and dispense history, express love or hate, expose a wrong or make us laugh can be found in these families. Anyone care to add to the list.
Don