Languages

I've asked this elsewhere, as have others, but I still haven't gotten any answer. I currently use English on my site. I have a sitewide child language of en called en_gd. I also have several child languages of en_gd called en_oe and en_me. As far as I understand, I need to rename en_gd to en_utf8_local for the database migration. But I have yet to read anything explaining how I handle en_oe and en_me. How do I rename these files? And do I need to indicate their parent languages somewhere inside the files? If so, how? And finally, what is the order that Moodle will check for language strings with these various packs in 1.6 when there is a course language? In 1.5 I could count on it, for example, looking for strings in en_oe, and then en_gd if they were missing from en_oe, and then finally en. Does it work the same in 1.6?