The files are named Virtual Families*.ldw, where * is a number corresponding to the player slot. There is also a backup savegame file for each game slot, which are named Virtual Families21.ldw through Virtual Families25.ldw.
Therefore if the first player listed in the options screen (before moving) is "knksmiles", say, they should get Virtual Families1.ldw and the backup, Virtual Families21.ldw. The second person listed would get Virtual Families2.ldw and Virtual Families22.ldw, and so on.
Note that I've never done this exact thing, but I have restored game files in the past successfully.
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To err is human; to arr is pirate.