In the February, 1970 Word Ways Darryl Francis had an article "A Reconstructable Crossword Puzzle". The 15x15 puzzle had fixed pieces (polyomino style) that could be moved around in the grid to form a second crossword with new definitions. Sometime later he sent to Word Ways a six-solution puzzle of a similar nature. This puzzle has not yet run in print because of space considerations but we hope to use this tour-de-force in the near future.
"Variation on a Theme of Francis,"
Word Ways: Vol. 41
, Article 15.
Available at: http://digitalcommons.butler.edu/wordways/vol41/iss3/15