3 Macbooks

Hi,
I have a question. I currently have 2 macbook airs running snow leopard.
I just bought a new Macbook Pro running lion.
Macbook Air 1 is on its last leg. Macbook Air 2 (my son's laptop) is in great shape. I just got him the new Macbook Pro.
So, I would like to transfer the contents of Macbook Air 1 to Macbook Air 2 AND transfer the contents of Macbook Air 2 to new Macbook Pro.
What process should I take? The new Macbook Pro says that I have to upgrade Macbook Air 2 to Lion before I can use migration assistant.
Can I use Migration Assistant to accomplish everything?
Thanks very much.

You should be able to use Time Machine instead. After getting everything you wish on to the good Air machine, make a complete Time Machine backup to an external drive. When your son turns on the new MBP it will ask him if he wishes to transfer files and the method. Choose Time Machine and attach the external drive to the MBP. The Time Machine backup will not overwrite any of the Lion system files, but it will transfer applications and settings along with any data, documents, etc.