importing from "filemaker runtime"

[phar]

very newbie here. i have an existing sales program someone wrote using "filemaker runtime". it operates on its own, meaning filemaker pro is not needed on the machine. i needed to make the program usable by multiple users on a lan, so i installed fmp on all machines and extracted the data files from the original program. it all works fine, but the data files have the extension ".leg" (??). i have to select "all files" when trying to open them with fmp. can i convert these few data files to a proper fmp extension? if so, how? just changing the extension did not work. thanks a million!