Who will be the Greek Sweeper?

I am still thinking about the Greek question and how Greece could leave the Euro.

In previous posts I have highlighted the question of a lack of physical currency stock and the difficulties of swapping it out. along with that there is, I feel, a real issue with how to draw a line around what comprises the Greek economy that will leave considerable imprecision about what would need to be converted by banks etc into the new currency, the New Drachma.

It is this latter issue I have been thinking about. I have only come up with one answer that is not simple and could have some serious implications. In  simple terms I do not think that the community will be able to issue rules that inherently create matched assets and liabilities in the New Drachma. This means that in keeping with the principles of double entry accounting there will need to be a sweep, a collection and consoliodation of all the mismatched balances. This I expect will have to be cumulative ie local banks reporting to a central bank who then, I expect will need to work with the ECB who I expect will have to take the full impact, taking the resultant exposure and providing corresponding compensation to the rest of the banking system.

Without this there could be considerable exposure in each regional (eg UK, US, etc) banking system. This would be unacceptable and create even more uncertainty and instability with each region trying to look after their own interests and exposed to the actions of speculators and hedge funds. This is not a recipe for financial stability.

Where any rules leave doubt or ambiguity I would expect enactors to take what they consider to be the most advantageous choice, which is probably leaving balances in Euros as I would expect the New Drachma to be pretty weak. This means that that non-Greek banks will try and keep as many of their assets, ie debt to Greek entities, in Euros while much of the resulting money will be converted into New Grachmas. 

Now I am not economist and I have to admit that I have not worked this all out and have no idea of the scale, but instinctively I believe I am on the right track - the risk and implications have to be "taken" centrally and I can see no other place than the ECB.

This could be a very interesting and difficult ride. I just hope bigger brains that mine are thinking about this and can come up with a better solution.