If you have a bunch of those names you want to edit, there's a much easier and faster way to do it. Do you have a spreadsheet program? If not, go get apache open office. It's free and all I ever use.
1. Export your leagues rosters.
Make a backup of your rosters.txt file first!!!!!
2. Load it up in your spreadsheet.
3. Change the players names and nothing else. If you have just a few, use the Find feature to locate them.
4. When your done, save it. Make sure it saves as a txt file in csv (comma separated) format. If it saves as a .csv file, no problem, just rename csv to txt.
5. Import it to your game. Now those players names are permanently changed.
When making the changes in the spreadsheet, Don't sort anything unless your 100% sure of what your doing. It's easy to mix up the player/team ID numbers. Keep all data unsorted.