You said, "对参加钢琴比赛的孩子来说，麻烦就大了。也许几个月的功夫白下了。评委是要看着谱子点评的
I don't think the judges would be that picky to a participant at your son's age and level. As long as you hand in the edition from which your son learnt, most of the judges are rather tolerant to discrepancy like that. It is true that some prestigious/pro level competitions are very particular on the editions but in those cases, the participants are told (at least recommended) what editions to use.
As one of the posts said, there are many editions on the market. Some are better than the others. The editing of Bastien Piano, Literature vol. 1-4, is so-so to today’s standard, though they sell well. It is because the editors (James & Jane Bastien) made their names through publishing a series of very successful method books, Bastien Piano Basics. However, the Bastiens are good at preparing materials at beginning level, while at intermediate-advanced level, their editing reveals their limitations. Particularly, it shows in its vol. 5, the newest addition to the series, edited by Jane Bastien alone. That volume is not only sloppily prepared, with tones of editorial mistakes, but also the editing standard was way below that of today.
If you really would like to find a good edition for you son’s competition, here is a more reliable edition: http://www.sheetmusicplus.com/title/Fur-Elise-and-Piano-Piece-in-B-flat-major/5676074
