Of cource that charter cant be too specific since we probably end up with different organisational forms in different countries but it whould mention the minimal requirements for that a country organization should uphold to be able to qualify for to be part of a greater organization.
I think that it's here that EU comes to play. I have no expertise in these matters, but I think it makes rather good sense that, if we're going to start this stuff and call it "FSF Europe", it should be based on a legal object which is defined by the EU.
The EU, as it stands, defines no such legal objects, I'm afraid. European law (contrary to popular belief in the UK, at least ;) does not occupy a position superior to national law. European law is there to enforce laws brought about by various harmonisation treaties, etc., and often gets incorporated into national law (witness the human rights stuff in the UK recently). The EU laws specifically do not harmonise many areas - company law being one of them. If you think about it, there is no such thing as a 'global' or 'world' court, yet we still have multinational companies. They have bases in many countries, and are a collective who act as a whole for their greater good, but there is no legal sense of 'multinational' as an object; it's a state rather than a object.
Cheers,
Alex.