Where to add the "extra" danish letters æ, ø, å in the scripts

An old question, but I have not been able to find a complete explanation.


URL to your site: www.byogland-nyborg.dk
Version of PHPFusion: 7.02.07
Any mods you've made to your site: Added some drop-down menus in the theme Revision. Added æ,ø,å,ü, ä, Æ,Ø,Å,Ü,Ä in the list of letters which are allowed to use in the user names.
Version of PHP: version 5.4
Version of MySQL: 5.0
Have you searched for your problem: (yes/no): Yes
If so, what terms did you try: Scandinavian letters
State the nature of your problem: I want to be able to add more letters to be allowed in user name and password and other places, where it can be useful for a Dane, but how many places has to be changed.
I have searched -0-9A and I have found the following php-scripts:
\administration\administrators.php
\administration\members.php
\administration\news.php
\administration\photoalbums.php
\administration\photos.php
\administration\updateuser.php
\administration\updateuser.php
\contact.php
\forum\postedit.php
\forum\postnewthread.php
\forum\postreply.php
\forum\postreply.php
\includes\classes\LostPassword.class.php
\includes\classes\UserFieldsInput.class.php
\infusions\news_letter_panel\news_letter_panel.php
\infusions\news_letter_panel\news_letter_subs.php
\htdocs\infusions\news_letter_panel\news_letter_uploads.php
\infusions\news_letter_panel\subscription.php
\register.php
\setup.php
\submit.php

Will You advice me to change -0-9A-Z_@\s to -0-9A-Z_@\sæøäöéåÆØÅÄÖÉ in all the scripts to make the danish site work with letters used in the danish language.
Of cource I have to change the locale-file too.

Thank You in advance. Jens Solvang