I have a DONE4, issued by AA Capetown. It was Africa-Europe-NA-Aust.

I am currently in Europe and it now looks as if I will need to travel to South America, rather than North America. I could add South America and make it a DONE5, but I would rather not do that because of the extra cost of the DONE5

I have 2 questions:
1. Are AA likely to allow me to change the segments & reissue the tickets, if it involves travelling Europe-South America-Aust, where there are no AA segments or codeshares (that I know of) that I can use.

2. If they will, I assume that my fuel surcharges will then be less, as AA generally only charge for AA segments across Atlantic/Pacific. Will they refund any of these?

Thanks in advance