Another one of those "two melodies to the same chord pattern, like "Real True Lovin'".  The important thing is to be sure that your counter melodies don't get in each other's way.  In other words, where you have a lot of words in one melody, try to put "footballs" (whole or half notes) in the other melody.  Also, "counter motion" seems to be called for in this type of format.  It's a fun exercise for songwriters, and sometimes you come up with something unique and unexpected!  I have a tape of the late Stephan Grapelli, who played jazz fiddle lines to a bunch of old standards, and renamed them in French.  The trick is to figure out what the original song was to that chord pattern.

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