We went to Donald's Safari breakfast in July and got a family portrait without any characters, and Donald was inside going between tables like the rest of the characters.
We went again in Sept/Oct and got a family portrait with Donald outside, but inside it was just the other characters, no Donald.
So we've had both experiences within just a couple months... not sure why, and I can't predict what they'll do next time! Sorry!
Maybe somebody else has more of a clue.