Hey I'm actually planning a trip to Rio and was looking at the same thing incase I get stuck and need to get to Sao Paulo.

Anyways, I like you saw that on TravelNet Delta doesn't have a Zed agreements with either of the Brazilian Airlines.

What is interesting is that if you go to GOL's website: Travel Agents

Then click on etkt interline agreements, It says on this page that we do have an agreement with them.

Best bet is to log onto delta term and try and book the flight or call the pass bureau