1. A method comprising: providing a copy of a computer file from a first computer to a second computer; modifying at said second computer said copy of said computer file to create a modified version of said computer file, maintaining a change log at said second computer, reflecting changes resulting from said modifying at said second computer; passing to said third computer, said modified version of said computer file, and entries of said change log at said second computer, modifying at said third computer, said modified version of said computer file, to create a further modified version of said computer file; maintaining a further change log, reflecting changes resulting from said modifying at said third computer; and at said first computer, synchronizing said computer file with said further modified version of said computer file using entries of said change log at said second computer and said further change log so that said computer file at said first computer includes modifications made at said second computer and said third computer.