2008/9/9 Andrew Whitworth wknight8111@gmail.com:
Being on the Chapcom, this is a question I'm actually qualified to answer. Even though groups are called "chapters" of the Wikimedia foundation, we try to make sure that they are all independent (but mutually supportive) organizations. To slice hairs, you are not a "child organization of the WMF", but instead you are an individual organization with common aims as the WMF (along with a few additional rights such as the use of trademarks and the right to represent the WMF to the press, etc).
I describe them to people as "sort of an official fan club - rights to use the name, but no money sent back up or whatever."
So, calling yourself "Wikimedia UK" overemphasizes and misrepresents your relationship to the WMF, and that's discouraged.
Though the organisation will trade under that name! But yes, it shouldn't be its real name.
(This is also so that, in the event of a chapter dying or going rogue, the Foundation can revoke its trademark licence [WMUK v1 had a 3-month notice period] and assign it to a viable new organisation.)
(On a related note, you should definitely run your bylaws and some other organizational details past the chapcom before you do anything legally binding, just in case you've made a decision that we don't approve of, which is admittedly rare).
This is a hard part in that every country's laws are different, yes :-)
- d.