The 2 year arrangement is extended to QAL crew and it applies to any QAL crew who go to A380 fleet until the 4th Aircraft Arrives.
After the 4th Aircraft then any crew who transfer to A380 from QAL do not get the Automatic right of return to 747 land. They would only be able to go back to 747 land depending on "operational requirements" and at the discretion of the business.
The "agreement" as outlined above is contained in an exchange of letters between the FAAA and Qantas along with other matters that by "workchoices" couldnt be contained in the EBA itself but can exist by virtue of the exchange of correspondence.
It is also contained in the application form and letters sent to the crew outlining the above conditions upon both application and and appointment to A380
It is also contained in material supplied by the company at roadshows they conduct and also outlined verbally at the roadshows
Hope that assists