Get the organizer's calendar appointment using EWS for Exchange 2010

Question

I have an synchronization application with sync appointments with Exchange 2010, and i have some questions.

1. UserA creates an appointment and add UserB as attendee, this means UserA is the organizer of the appointment and UserB outlook calendar will have an appointment entry created.
2. UserA and UserB calendar appointment will have their own IDs (UniqueID).
3. If for example i am only given the ID (UniqueID) of UserB's calendar appointment, is that a method to retrieve UserA's calendar appointment? Because i think they should be some link between the organizer and the attendees appointment, i just don't know how.