Does anybody know the composition of the 6th council and how the delegates were chosen? Nyanatiloka and Nyanaponika were the only Western born monks to attend the 6th Council. I am curious to know the composition of the 6th council and how the delegates were chosen.

Wikipedia says:


  The council was attended by 2,500 monastics from eight Theravada Buddhist countries.


Clearly there would have been more countries involved than the 8 Buddhist countries. Also the delegates from countries which were not predominantly Buddhist sponsored by a Buddhist country they lived in. Also how come Nanamoli Bhikkhu and Ven. Ñāṇavīra Thera did not make it as delegates?
I have been asking around and done some research, but got nothing specific to answer your questions. Some years ago I spoke with an elder Norwegian Buddhist, who said that no less than 12 countries(to his knowledge) was present, plus a number of schools from each country. He said that extra invitations were sent out by the original invited and that this was allowed. A bit like how the Buddhist UN conferences work - just without all the fancy food... :)