- as site language you take en_hsu and you call it en_hsu_utf8
- the other language packs, you call e.g. en_hsucosmos_utf8 and en _hsusports_utf8 and you add in each langconfig.php of those two language packs (or in moodle.php of them) the line $string[parentlanguage] = en_hsu_utf8;
- en_utf8 will automatically be the default to resolve all strings not in your language packs, so no actions to take for that
For more details, please see the information on custom language packs in the Upgrading to Moodle 1.6 documentation . You can find that by following this link: http://docs.moodle.org/en/Upgrading_to_Moodle_1.6