I will be attempting to secure ff tickets (Tucson - Johannesburg, Rio - Tucson) while on our LAMB cruise. So, today I called United one more time. Here's the advice the agent gave me:

On Dec. 16, book the Nov. 11, 2008 outbound flight from Tucson to Frankfurt on United. Because it is a United flight they will hold for the return.

Then, on Jan 5, book the Dec. 4, 2008 return flight from Rio. At the same time, request the Frankfurt to Johannesburg leg of outgoing flight.

Total miles required for the round-trip, open-jaw trip: 120,000pp for business.

I never quite trust advice from United agents who live in India and barely speak English. What do you experts think? Did the agent give me good advice or steer me in the wrong direction.