So, after various bits of discussion, I believe the situation is as follows:
1) Convoy "blesses" an event for Easter 2007 (a replacement Eastercon/Eastercon-lite/whatever) then, since we voted for Convoy to organise an Eastercon, the replacement event carries the tranferred authority and so ...
... we have a standard business meeting at the replacment con and people vote *at* the business meeting to select the 2009 Eastercon (as normal)
2) No clear replacement event is run at Easter 2007, in which case we need to find some other way of allowing the will of Eastercon fandom to select the 2009 event (options include one year voting at Orbital 2008, polling the members of either Convoy, or Orbital, or Concussion, or some variant on the proposal I put forward earlier in this community)
NOTE: At the moment we're very hopeful we'll have a single major event for Easter 2007, and that Convoy will bless it. Therefore, if the replacment event goes ahead, the site selection for 2009 *will* be held at the "replacercon".