Does anyone knows a software (or url) which merges two sgf files into one sgf file?

I've added comments, board markup, variants (etc.) to a sgf file, and my opponent has done the same. Of course our comments are not identicial, but they are based upon the same game.

What is the easiest way to merge these two sgf files into one sgf file? The resulting sgf file should contain all comments (etc.) from both source sgf files …

Additional note: sgfMerger by KGS developer Bill Shubert is a command-line java program that combines multiple SGF games into a single SGF file. It is useful to create a game collection for distribution in a single SGF file. _But_ it does _not_ merge two SGFs which are based upon the same game into one SGF.