The accompanist as editor . . . and re-composer

On This Blog Will Change the World, the author talks about how organists/accompanists edit the work in order to make it work for their instrument.

He writes:

Most people, even other musicians, are probably not aware of the extent to which the organist-accompanist creates his own score for the works he performs. A part like "How dazzling fair" can be played as written and sound fairly good--the Glick, on the other hand, is literally unplayable as it appears in the score and requires extensive modification. As a collaborative pianist, your role is comparatively simple - to play the score accurately and musically, while being sensitive to the needs of the soloist or ensemble that you're accompanying. (I still do quite a lot of collaborative piano work, and can vouch for the fact that this is no easy task!)

Look here for the full discussion of the process.