Yes, if you go to the top of the page to the advanced search and put in coscoroba swans, there are a few threads you´ll find. I have the normal....geese, ducks, chickens.
I read that coscoroba swans are more like goose-swans, so maybe they´d get on better with some geese as companions than the swans. i suppose it´d be worth experimenting? Just a thought, but have you looked at the threads on BYC about swans? You may find some more information there, or people...
Well, if the males get along, of course, it´s no big deal. Howerver, as you said, you could always give them a couple of domesticated geese, they´d probably be quite happy. :)